Preheat the oven to 350 degrees . In a small bowl, stir together the yogurt and 2 tablespoons chopped cilantro. Wrap the tortillas in foil and heat in the oven for 15 minutes.
Meanwhile, in a large nonstick skillet, heat 2 tablespoons olive oil over medium-high heat; add the onion, season with salt and black pepper and cook until browned, about 12 minutes. Add the tomatoes, increase the heat and cook until the liquid evaporates, about 3 minutes; transfer to a bowl.
Add the remaining 2 tablespoons olive oil, the garlic and crushed red pepper to the skillet and cook over medium-high heat for 1 minute. Add the shrimp, season with salt and black pepper and cook until just pink and opaque, 3 to 5 minutes; stir in the remaining 2 tablespoons chopped cilantro. Serve with the tortillas, onion mixture, yogurt and cilantro leaves.
