How to Make It
In a large skillet, heat 3 tablespoons of the olive oil. Add the onions and cook over moderately high heat until lightly caramelized, 8 minutes. Add the tomato paste and crushed red pepper and cook for 2 minutes. Stir in the olives and tomatoes. Season with salt and black pepper and let cool.
In a bowl, whisk the yeast, sugar and water; let stand until foamy, 10 minutes. Whisk in the remaining 2 tablespoons of oil and 1 teaspoon of salt. Stir in the 2 1/2 cups of flour and the semolina until the dough comes together; it will be quite wet. Stir in the cooled olive mixture. Cover the dough with a damp kitchen towel. Let stand in a warm spot until doubled in bulk, about 1 1/2 hours.
Preheat the oven to 450°. Scrape the dough out onto a well-floured work surface. Shape it into 2 rough 14-by-3 1/2-inch loaves and transfer to a parchment paper–lined baking sheet. Bake for 25 minutes, until the loaves are lightly browned and risen; transfer to a rack and let cool completely.