She also includes a trick useful to anyone caramelizing onions: Add a tiny amount of baking soda (1/8 teaspoon) to decrease the acidity of the onions and allow them to brown faster without losing as much moisture.
Caramelized Onion Focaccia
2 cups tapioca starch
1 cup light buckwheat flour
1 tsp. salt
1 cup milk
3 Tbsp. olive oil
1 Tbsp. active dry yeast
1 tsp. sugar
1 large egg
2 Tbsp. olive oil
1 medium sweet onion, thinly sliced
1/2 tsp. salt
1/8 tsp. baking soda
2 tsp. chopped fresh rosemary
Make the focaccia dough: In a food processor, combine the tapioca starch, buckwheat flour and salt and pulse until blended.
In a medium saucepan, bring the milk and oil to a boil, stirring constantly. Immediately pour the hot mixture into the dry mixture and process until it is moist with a sand-like texture. Allow the dough to cool for 20 minutes.
Meanwhile, in a small bowl, combine the yeast, sugar and 1/3 cup warm water and allow it to proof for 15 minutes.
Add the yeast mixture and egg to the dough and blend until it is smooth. Scoop the dough into a large bowl, cover it with plastic wrap, and let it rise in a warm area until doubled, typically about 1 hour.
While the dough rises, make the caramelized onions: In a 12-inch skillet, heat the oil over medium heat. Add the sliced onions, salt and baking soda and cook until just browned. Set the skillet aside.
Position an oven rack in the center of the oven and heat to 400 degrees. Grease two 9-inch round cake pans and line each with a round of parchment paper. Punch down the dough with a rubber spatula and divide it in half. With wet hands, shape each dough half into a mound, and place each one in a cake pan. Press the dough evenly into the pan. Wet your fingers and press them lightly into the tops of the mounds to create depressions.
Top each mound with the caramelized onions (including any of the onion cooking oil), spreading them over the top and into the depressions. Sprinkle the chopped rosemary over the top. Allow the dough to rise uncovered for 45 minutes, or until it is puffy. It will not rise a lot with the oil and the weight of the onions.
Bake the focaccia for 30 minutes, or until browned and fragrant. Transfer the focaccia from the pans to a cooling rack to cool completely. Makes two 9-inch focaccia.
— From "Against the Grain: Extraordinary Gluten-Free Recipes Made from Real, All-Natural Ingredients" by Nancy Cain (Clarkson Potter, $27.50)
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