Onion, Tomato, and Olive Pizzas

Put oven rack in middle position and preheat oven to 475 °F. Line a large baking sheet with parchment paper. Cook onions, garlic, anchovy paste, salt, pepper, and sugar in oil in a 12-inch heavy skillet over moderate heat, stirring frequently, until onions are caramelized and very soft, 25 to 30 minutes. Divide dough into 4 pieces and gently stretch each into a 5-inch square, then transfer to baking sheet. Spread onion mixture over each square, leaving a 1/4-inch border around edges, then top with tomato slices. Bake pizzas until edges of dough are golden, 12 to 18 minutes. Toss together olives and thyme and sprinkle over pizzas. Quarter each square diagonally, making 4 triangles, then cut each triangle in half. Sprinkle with sea salt. *Available at specialty foods shops and Salt Works (800-353-7258).