Heat olive oil in a paella pan or wide skillet over medium heat.
Sauté the onion and red bell pepper until softened, about 5 minutes.
Stir in the minced garlic, smoked paprika, and tomato puree, cooking for 2 minutes until fragrant.
Add the Bomba rice and stir to coat each grain in the tomato mixture.
Pour in the seafood stock and add the saffron threads, sea salt, and black pepper.
Bring to a boil, then reduce heat to a simmer and cook undisturbed for 10 minutes.
Nestle the shrimp, mussels, and squid rings into the rice.
Scatter the green peas over the top and continue to simmer for 8-10 minutes until the seafood is cooked and liquid is absorbed.
Increase heat to medium-high for 1 minute to create a crispy rice bottom known as the socarrat.
Remove from heat, cover with a towel for 5 minutes, then garnish with parsley and lemon before serving.