In a small bowl, soak the saffron threads in 2 tablespoons of warm seafood stock and set aside.
Heat olive oil in a large paella pan or wide skillet over medium heat.
Add the chopped onion and diced red bell pepper to the pan and sauté for 5 minutes until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Stir in the rice, smoked paprika, salt, and black pepper, coating the rice evenly with the oil and vegetables.
Pour in the diced tomatoes and the remaining seafood stock along with the saffron-infused stock. Stir to combine.
Bring the mixture to a boil, then reduce heat to medium-low and simmer uncovered for 15 minutes without stirring.
Arrange the shrimp, mussels, clams, and squid rings evenly over the rice mixture.
Continue cooking for another 15 minutes, or until the seafood is cooked through and the rice is tender. Avoid stirring to allow a crust to form on the bottom.
Scatter the frozen peas over the top during the last 5 minutes of cooking.
Remove the pan from heat and cover loosely with foil. Let rest for 5 minutes.
Sprinkle chopped fresh parsley over the paella and serve with lemon wedges on the side.