Catalan Flatbread with Spinach, Onion and Pine Nut Topping

Description
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Ingredients

 * Topping
 * 1 1/2 cups unbleached all-purpose flour
 * 1/2 cup yellow cornmeal, plus more for dusting
 * 1 ( 1/4-oz.) pkg. quick-rising dry yeast
 * 1 tsp. salt
 * 1/2 tsp. granulated sugar
 * 2 tsp. olive oil

Directions
1. Begin topping: In large skillet, heat 2 teaspoons oil over medium heat. Add onions and 1/2 teaspoon salt; cook, stirring often, until very tender and lightly browned, 20 to 25 minutes. To prevent scorching, adjust heat and add water as necessary.

2. In food processor fitted with metal blade, make dough: Combine flour, cornmeal, yeast, salt and sugar and pulse on/off to mix. In measuring cup, combine 2/3 cup hot water (120F to 130F) and 2 teaspoons oil. With motor running, gradually pour hot liquid through food processor feed tube. Process until dough forms ball, then process 1 minute to knead. The dough should be quite soft. If it seems dry, add 1 to 2 tablespoons warm water; if too sticky, add 1 to 2 tablespoons flour. Transfer dough to lightly floured surface and knead a few times. Lightly coat large sheet of plastic wrap with cooking spray and place, sprayed side down, over dough. Let dough rest 20 to 30 minutes.

3. Meanwhile, place baking stone or inverted baking sheet on bottom rack of oven to heat. Preheat oven to 450F. (Heat baking stone for 25 minutes before baking; heat baking sheet for 10 minutes.)

4. In small bowl, cover currants with hot water. Set aside to soak about 20 minutes. Drain and stir currants into onions. Stir in vinegar and pepper.

5. In small baking pan, spread pine nuts and toast in oven until lightly golden, 3 to 4 minutes.

6. In large wide pot, cook spinach with just the water that clings to leaves over medium-high heat, stirring often, until wilted, 3 to 5 minutes. Drain in colander. Rinse with cold water and squeeze out excess moisture. Place in medium bowl and add remaining 1/2 teaspoon salt.

7. Assemble flatbread: Coat baking sheet with cooking spray and dust with cornmeal. On lightly floured surface, use rolling pin to roll dough into 16 x 12-inch rectangle, slightly less than 1/4 inch thick. Transfer dough to prepared sheet. Roll edges under to finish rim of crust. Brush remaining 1 teaspoon oil over rim of crust. Scatter spinach over crust. Top with caramelized onion mixture and sprinkle with toasted pine nuts. Lightly coat topping with cooking spray.

8. Place baking sheet on heated baking stone and bake until bottom of crust is golden and crisp, 20 to 25 minutes. Transfer to cutting board and use pizza cutter to cut into 8 rectangles. Serve hot or warm.