It may seem strange to have a dish using couscous (made of semolina flour) in an Italian cookbook, but couscous is actually a staple of Sicilian cooking. Over the centuries, southern Italian—and especially Sicilian—culture has been greatly influenced by North Africa and Greece, and this recipe is a perfect culinary example.
n a Large Pot, heat ¼ cup of the oil over a medium-high flame. When almost smoking, add the onion, carrot, and half of the garlic and sauté until the onion is soft, about 5 minutes. Add the tomatoes with their juice, clam juice, wine, ½ teaspoon of salt, and ¼ teaspoon of black pepper. Bring to a boil and simmer uncovered over medium heat until the liquid reduces and the tomatoes break down, about 10 minutes. Remove from the heat and let cool slightly. Carefully transfer the tomato mixture to the bowl of a food processor and purée until smooth, adding water a couple of tablespoons at a time to form a broth consistency. (The tomato broth can be made 1 day ahead. Cool, then cover and refrigerate. Bring the tomato broth to a simmer before continuing.)
In a medium saucepan, combine 2 cups of the tomato broth, 1 cup of water, and 1 tablespoon of oil. Bring the mixture to a boil, then stir in the couscous. Remove from the heat. Cover and set aside until the couscous has absorbed the liquid, about 10 minutes. Season the couscous with more salt and pepper to taste. Keep the remaining tomato broth warm.
In a large skillet, heat the remaining ¼ cup of oil over a medium flame. Add the remaining garlic and sauté until fragrant, about 20 seconds. Add the shrimp and sauté until the shrimp just begin to turn pink, about 5 minutes (be careful not to overcook the shrimp or they will become tough). Remove from the heat and stir in the lemon juice, parsley, red pepper flakes, and the remaining ½ teaspoon of salt.
Spoon the couscous into the center of serving plates and top with the shrimp. Spoon some of the remaining tomato broth around the couscous and serve.