Bakeries boast if they use a brick oven for their breads.  Why? 
These ovens cook using multiple forms of heat- conduction, radiant, and direct heat.  Add some steam, and you get some seriously fabulous crust on your bread.  Pizza?  You better believe it.  You cook it at an ideal 700 degrees Fahrenheit; a thin-crust pizza is done after only 3 minutes, emerging bubbling and with a lovely smoky flavor.
Cook anything in this that you would in a regular oven.  And when it's cooled down, it can remain the ideal temperature for incubating yogurt, clear through the night.

This type of oven has the fire built on the cooking floor.  Fill the oven with wood, light it, and let it burn for 2-4 hours, until the oven walls glow white-hot.  My thermometer doesn't measure high enough to know how hot this is; it only measures to about 1400 degrees!

Scrape out the fire, quickly scrub off the oven floor, and let the heat "soak"- you're letting the temperature equalize all over the interior.  When the temperature has dropped to what you want, add some steam (for bread baking) by swabbing the oven floor with a wet cloth or mop.  Load it up with your bread, or turkey, or squash, potatoes, casserole, or whatever-- and close the oven door to bake.


It's called an earth oven because it's made using packed earth; in other words, mud.  This makes it very affordable!  I highly recommend Kiko Denzer's book, Build Your Own Earth Oven.  It was invaluable to me, and has many excellent suggestions for making do with what you have locally.  He also has a great overview on Mother Earth News, right here.
You can make a fabulous oven out of nothing but dirt, sand, chopped hay or leaves, and some bricks or tiles.  There are even simpler versions around, using just rocks and dirt. 

Since I opted for several upgrades on this oven, it cost about $200 total. 

Items I got for free:
cinderblocks (a stack was in the yard when we bought the house)
sand (huge sandbox, in the photos' background)
bricks for the oven face

Items purchased included:
bags of cement for a foundation pad
rebar for reinforcing the foundation
rebar for reinforcing the cinder blocks
cement for reinforcing cinder block construction
one used steel entry door
one circular saw blade to cut the steel entry door
about 45 firebricks
1/2 cubic yard of dirt
a couple small buckets of refractory cement
portland cement and a bag of vermiculite, for the insulation layer.
12" of 1" diameter steel electrical duct tubing
one dial-gauge thermometer
mortar, used with the oven face, and some gaps in the cinderblocks

If the pictures below seem overwhelming, here are the steps in short form- prepare an insulated base for the oven; build a sand dome on it; pack moist earth all around  the dome (thermal layer); pack insulation around the thermal layer.  Finish with a breatheable plaster, for longest-lasting results.  The doorway can be molded in as you go, or carved out afterwards.

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Sorry, I didn't take any photos before this point.  I poured a slightly sloped foundation pad, reinforced it with rebar, and dry-stacked cinderblocks, leaving some slots for drainage between cinderblocks at the low part (the back) of the pad.  To reinforce the cinderblock walls, I stuck rebar down every 2-3 cells, then filled those (with rebar) with cement.  (I did this because I have roughhousing boys, and live nearby a major  fault line.)  In this photo, half of it is in shadow; the oven floor is meant to be just above waist-high.  The area under the oven is to store wood.  To support the block over the opening, I found a piece of hardi-backer (cement) board.  The top course of cinderblocks were narrower than the ones below, which gave me a spot to place some kind of support for the oven floor.  I bought a used steel entry door and a special saw blade, and cut the door to fit.  On top of that went a layer of sand, for insulation, filled even with the top of the blocks (packed really well).  Firebricks were set snugly together for the oven floor, and a circle scribed in chalk.  This would be the inner diameter of the oven.

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The sand was free, but it had lots of rocks- and small toys- mixed with it.  A frame with 1/2" hardware cloth stapled to it worked well for sifting.  If you notice my expanding waist in the next photos, it's because I was 8 months pregnant when I started this project, and 9 months along when it finished.

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Build a dome of moist sand; this will be your oven's hollow part later.  There's a height-to-width radio that works most efficiently, but about ratio will give you an oven that cooks. 
The pipe in the middle was to show my required finished height.  Pack the sand really well, or it won't support the weight you're about to put on it.

TIP:  this takes a TON of sand, which you'll have to scoop out later.  At about this point I started added cinderblocks and other large items to the dome. That saved a lot of scooping.  And sifting.

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Once the dome is as big as you want, pack and smooth it as best you can. A little water helps, and a board to press and smooth. 
If you want a layer of refractory cement, to help hold heat and protect the inside walls, add it now.  A thin layer, 1/8 - 1/4 " thick, is all you need.

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Once that's in place, mix your dirt- er, I mean 'earth'.  It needs to be moist enough to hold together, but not so wet it squishes when you pack it.  You can mix it on a tarp with your feet, or in a wheelbarrow with a shovel.  Starting at the bottom, tightly pack this earth in a layer about 4" high, and the width of your hand.  Use your closed fist to pack it, and a small bucket of the dirt to keep it handy. Spiral your way up the dome, always packing hard onto the layer below.  Don't apply any pressure to the sand dome.  Let this sit for a few days, then scoop out all the sand.

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Once the earth layer is complete, add an insulation layer in the same way as the earth layer.  This makes a huge difference in how well your oven retains heat.  You can use more mud, mixed with any organic material- chopped leaves, straw, horse hair, you name it.  They will burn out when the oven heats up, leaving insulating air pockets behind.  This oven's insulation is a mixture of portland cement and vermiculite; I wanted it to be very durable.  Shape this layer with your oven door in place so it fits. 

The pipe sticking out in front of my face is a piece of metal conduit with a fitting to screw on the temperature gauge.  Next time I'll put it down close to the oven floor, which is where the bread bakes.  There's actually about 100-degree (Fahrenheit) difference between the oven floor and where the oven probe sits. 

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If you want the oven to dry with as few cracks as possible, build a low fire and let it burn for several hours.


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For a brick face-  a chisel and hammer yielded a really poor keystone for the arch.  Improvise to support the arch until it dries.   A bucket and cinderblock came to the rescue here.

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The completed oven. 

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More completed, with flagstones set around it. 

When using the oven, keep a bucket of water handy. 

I still intend to make a roof for it- Utah winters are rough on it.  There are two eye bolts embedded in the top of the oven- all it will take is a piece of sheet metal, creased at the center to make a sloping roof, and two slits cut in it to slip over the eye bolts.  Twist them, and it should stay on.

 
 
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The BYU Solar Cooker- designed to work well with whatever materials you have on hand to build with.  This one uses cardboard, foil, and a box to support it, though a bucket or some rocks would work too.

(Originally from 7/01/10)

I'm excited right now because this idea works!  Last week I cooked some carrot cake in a really
cheap and simple solar cooker. I got a windowshade at D.I. for $1.50, used a canning jar spray-painted black for a cooking pot, and fastened the edges of the shade with  metal brads (like you use in kids’ projects).  I set it outside, angled it so my shade fell right into from in front, and left it for an hour.  Yummy!   Not only that, but my 'carrot cake' was just my simple muffin recipe with cinnamon, raisins, and a handful of dried (not reconstituted, either) carrots from the Family Home Storage Center


So how did I make it?  Mine looked like these two solar cookers- the first uses that car windowshade, and the second just uses cardboard and aluminum foil.  Both designs are VERY similar, they just use different materials.  Use what you have; if you didn’t have aluminum foil but had one of those Mylar emergency blankets, you could use that.  Solar cooking works best from March through October, though you can still use your solar cooker in the cooler months.  It helps to put the cooker against a south-facing wall, to get more reflected energy, during the ‘off’ months.  Here’s the first link:  http://www.solarcooking.org/plans/windshield-cooker.htm .  The other version (from Dr. Steven Jones @ BYU) is made with cardboard and aluminum foil; the website has great info on why, how, and what to cook, including cooking times.  You can even make ICE with a solar cooker.  No kidding. It's at  http://solarcooking.org/plans/funnel.htm  This link also has cooking times for different types of food.


To cook a meal for a family, one way to cook a bigger amount is just use a bigger container.   Maybe layer multiple containers? Or layer food in one container. Usually not every part of a meal needs cooked, anyway.  I have pans that stack together, to cook things simultaneously.  You could also use a gallon-sized glass jar painted black; I got a couple from a store that makes chocolates.  They got the jars when full of maraschino cherries, and sold them to me (empty) for $1.  But any container that is dark (black or dark blue) can be cooked in.  Maybe use a Dutch Oven or enameled cooking pot.

And if you wonder why the instructions for the foil/cardboard solar cooker say to put a wooden block under the jar/pan before cooking, I found out why-  it's to keep heat from escaping out from underneath.  The first time I cooked with this, my carrot cake was a little underdone on the bottom.  Apparently that's why.  

 
I have also baked cookies in my van window.  I was told that it has to be at least 95 degrees outside for that to work, it gets to about 250 degrees in the window that way.  I tried it on  a slightly cooler day (93?) and it worked, barely.  Now if you put the food next to the glass, and put a sunshade BEHIND the food, on the dashboard, that might give you a much warmer (and bigger) cooking spot. Hopefully it doesn't bake your dashboard!  The glass IS tempered, though, so that part should be OK. 


You can also use a vehicle for dehydrating food because it gets so hot. Just be sure to open windows a bit for airflow. ( I haven't tried that one yet, though.)  You can use clean window screens or an old screen door for a drying tray.  Cookie sheets work, too, but drying will take a little longer because the bottom can’t get air.

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Those of you who planted potatoes this year probably now have those delicious, creamy ‘new potatoes’ ready.  (Or just use whatever kind from the store….)  Maybe try cooking these in your solar oven!
 
Oven-Fried Potatoes 

2-10  potatoes- however many you want   
1-2   Tbsp.   vegetable oil   
Seasoned salt, dry ranch dressing mix, or Parmesan cheese   

Heat oven to 450 degrees.  Wash potatoes well, then cut into strips or wedges about 1/4-1/2-inch thick , unless they're 'new potatoes'; leave those whole or cut into bite-sized pieces.  Put them all in a bowl, drizzle the oil over them, and then sprinkle a good amount of seasoned salt, dressing mix, or Parmesan cheese over the top.  Stir well and add more salt or cheese if it looks like they need it.  Spread potatoes out on an ungreased cookie sheet.  Bake for about 15-30 minutes or until lightly browned and tender when you poke the thickest one with a fork.