This delightfully soft and slightly chewy flatbread hails northern Sweden where it is known as tunnbröd (literally "thin bread"). Usually made from some combination of wheat, barley and/or rye flour, tunnbröd is traditionally baked quickly in a hot wood-fired oven. This recipe for tunnbröd couldn't be easier: a simple yeast dough is rolled thin and cooked quickly in a hot cast iron skillet.