Set up the Weber kettle for a two-zone fire (coals on one side). Heat the Dutch oven directly over the coals until hot.
Add olive oil, onion, and red pepper. Cook 5-7 minutes until softened. Add garlic and cook 30 seconds.
Stir in smoked paprika, saffron, salt, and pepper. Let bloom 20-30 seconds.
Add the rice and stir to coat in the oil and spices for 1-2 minutes.
Pour in broth, crushed tomatoes, and peas. Bring to a simmer, then move the Dutch oven slightly off direct heat. Do not stir again.
Cook 20-25 minutes until the rice is tender and most liquid is absorbed. Add a splash of broth if it dries too quickly.
Place mussels and clams on top for the last 10 minutes. Add cooked shrimp for the final 5 minutes.
Move the Dutch oven back over direct heat for 3-5 minutes until you hear gentle crackling from the bottom.
Rest 5 minutes off heat. Squeeze lemon over top and garnish with parsley, chili flakes, and olive oil.
Notes
Macros per serving: 38g protein | 12g fat | 52g carbs | 480 calories. Do not stir the rice once liquid is added. Listen for crackling to know the socarrat is forming.