Heat olive oil in a large pan over medium heat. Sauté chopped onion, garlic, and bell pepper until soft. Stir in paprika and rice, coating well. Add chopped tomatoes and cook for 2 minutes. Pour in hot stock with saffron and bring to a simmer. Cook for 10 minutes without stirring. Add prawns, mussels, and peas on top. Cover and cook for 10–15 minutes more until seafood is cooked and rice is tender. Let rest 5 minutes before serving with lemon wedges.