Heat olive oil in a large paella pan or a wide, shallow skillet over medium heat.
Add the chopped onion and sauté until translucent, about 5 minutes.
Stir in the minced garlic, smoked paprika, and saffron threads, cooking for another minute until fragrant.
Add the diced tomatoes and cook for 3-4 minutes until they begin to break down.
Stir in the rice, ensuring it is well coated with the tomato mixture.
Pour in the broth and bring the mixture to a gentle boil.
Add the shrimp, mussels, and calamari, distributing them evenly across the pan.
Lower the heat to medium-low and let the paella cook without stirring, for about 20-25 minutes, until most of the liquid is absorbed and the rice is cooked.
Sprinkle the peas over the top during the last 5 minutes of cooking.
Remove the pan from the heat and cover with a clean kitchen towel. Let the paella rest for 5 minutes before serving.
Garnish with chopped parsley and serve with lemon wedges.