Heat olive oil in a large paella pan or skillet over medium heat. Add the onion, garlic, and bell pepper, and sauté for 3-4 minutes until softened.
Stir in the rice, smoked paprika, and saffron (along with its soaking water), coating the rice in the oil and spices.
Pour in the seafood stock, season with salt and black pepper, and bring to a simmer.
Cook uncovered over medium-low heat for 15 minutes, stirring occasionally.
Arrange the mussels, shrimp, and squid on top of the rice. Cover and cook for another 10 minutes until the seafood is cooked and the rice is tender.
Add the peas and cook for an additional 5 minutes.
Remove from heat, garnish with fresh parsley and lemon wedges, and serve hot.