I made this flatbread the other night as an accompaniment to dinner. Within two or three bites it quickly became the main part of the meal and the pasta that went with it the side dish. The next time I made it it WAS the meal.
Two things I thought I never would like --onions & mushrooms-- have become two of my favorite things. I have a pasta recipe that I make that combines the two of them together but I wanted another way to have them together. One night, while thinking about making a carmelized onion pizza I saw the mushrooms and in my fridge and decided to go for it.
The flatbread is crisp on the outside with pillowy softness on the inside. Think of a thick pizza crust brushed with olive oil and sprinkled with coarse sea salt. Onions are carmelized until they are deliciously sweet. Mushrooms are sauteed with the onions and a bit of slivered garlic is tossed in to bridge the gap between sweet and earthy.
The glistening topping is spooned over the hot baked flatbread just before it's served. The combination of textures takes this flatbread beyond the usual mushy-ness we've come to expect from the new restaurant hype of attempting various flatbreads. The sea salt plays nicely against the sweetness of the onions to prevent the flatbread from becoming too cloying.

Indeed it is a perfect meld of flavors and well worth the time it takes to complete the several, but easy steps to prepare it.
Carmelized Onions & Mushroom Flatbread
by Michelle
For the topping:
1 extra large onion, or 2 cups onion sliced
12 ounces of baby portobella mushrooms, sliced
2 cloves of garlic, slivered
1 tsp of sugar (optional)
1 tblsp olive oil
2 tblsp butter
coarse sea salt
For the flatbread:
2.5-3 cups flour
1 tsp yeast
2 tsp sugar
3 tsp salt
1 tbsp olive oil
7-8 ounces of warm water.
1. Mix the dry flatbread ingredients. Then, mix in the olive oil and the water to form a shaggy dough. Knead 5-7 minutes with a mixer, a little longer by hand, to form a smooth dough. It should be soft, but not sticky. A tiny bit tacky is okay.
2. Place the dough in a well-oiled bowl, cover and refrigerate until 90 minutes before you plan to bake it. Holding the dough in the refrigerator for at least four hours is ideal, to help develop flavor, and overnight and until dinner the next day is fine too. It's not recommended to refrigerate any longer.
3. Remove the dough from the refrigerator and set on a draft free counter for about 60 minutes.
4. After about 20 minutes, in a large pan with a lid, heat up the 1 tbsp of olive oil over medium high and add the onions. Cook for 2 minutes, stir in the sugar if desired and turn down the heat to the lowest setting. Put the lid on and cook for about an hour. Stir occasionally, letting the onions slowly carmelize and become a deep shade of brown. If they are cooking too fast, you might need to remove the pan from the heat for a short time.
5. On a cookie sheet or parchment paper sprinkled with semolina flour or cornmeal, pat dough out into a rectangular shape about 1/2 thick. Cover loosely with a clean towel or oiled plastic wrap. Heat oven to 500.
6. Brush the dough with olive oil and sprinkle with coarse sea salt and place in the oven. Bake 10-12 minutes or until golden brown. Meanwhile, add the butter and mushrooms to the pan with the onions. Turn the heat up to medium high and cook until mushrooms are nearly fully cooked. Add the slivers of garlic for the last 2 minutes, stirring occasionally. Remove from heat.
7. Cut the hot flatbread into 6 generous portions. Spoon the mushroom-onion topping on the flatbread and serve hot.