I bought a Big Green Egg after other owners convinced me it worked beautifully as a hearth oven. So I fired it up last weekend with more than a little trepidation: would it really work well, or did I just buy an overhyped charcoal grill?
I made a batch of pain de campagne (white flour with a bit of rye for color & flavor), shaping the loaves to fit on the 14″ round baking stone. The stone sits atop a ceramic heat diffuser (BGE calls it a plate setter), which absorb heat from the charcoal fire directly below. I lit the fire, waited for the oven to hit 450-500 degrees (about 20 minutes, faster than my indoor gas oven), and loaded the loaves. 25 minutes later, I had the proof: the damn thing works GREAT as a hearth oven.
I still need to experiment with steam at the start of baking. I will try to heat a small cast iron skillet along with the baking stone, and I’ll add a few ice cubes to it when I load the bread (precisely how I steam in an indoor oven). Except the BGE is vented (unlike a home oven), and the steam may just rise right out the top. So I don’t know if I’m wasting my time, but I’ll find out this weekend…
Bouillie 
any way you can put the cast iron pan just below the bread so the steam hits it before exiting?
Not in the Egg, unfortunately. Due to the need for airflow, the plate setter (a ceramic thingy used when you want indirect heat) prevents you from using anything between the stone and the setter. So I’m going to try to put the pan beside the bread and see how that works…
If you wanted steam under the loaf, purchase a raised grid which will give you a tray above the plate setter (which will hold your cast iron pan). I have baked many loafs in the BGE, and it is great.
Wait, explain it again, only more slowly. I’m confused: if I want steam under the loaf, I can indeed use a raised grid & put the steam pan underneath (on the plate setter itself) then the baking stone & loaf atop the raised grid. But this means that the baking stone won’t be directly on the plate setter; doesn’t this decrease its efficiency? I’m shooting for crusty pain de campagne that bakes directly on the stone at around 500-550 degrees.
On your raised grid, have another baking stone, and as the Egg heats up, it will heat up as well. You would never put a cold stone in with the temperature around 500 degrees (it would probably crack). Also, the higher it is in the Egg, the hotter it will be (even though the plate setter is directly above the charcoal). If I want to cook my bread lower in the Egg, I put my baking stone atop the plate setter ( I have never cooked directly on the plate setter before). Try it and see if it works out. I would be concerned with the temp.difference when you pour the water or ice in the fry pan. Make sure you waer oven mitts to prevent a steam burn! Also, check out the naked Wiz’s site for the warning on flashback when you are cooking at those temperatures. http://nakedwhiz.com/ceramic.htm
I use a cast iron steam pan in my gas oven all the time at 550 degrees; no problems with steam burns or cracking…..I generally use ice, as it’s lots easier to add ice to the hot pan, rather than pour in water. I guess I need to get that raised grid after all!
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