In a small bowl, crush the saffron threads into the seafood stock and let it sit for 10 minutes to infuse.
Heat the olive oil in a wide, shallow paella pan or skillet over medium heat.
Add the diced onion and red bell pepper to the pan, sautéing until the vegetables are soft and translucent.
Stir in the minced garlic, smoked paprika, and tomato puree, cooking for 2 minutes until the mixture is thick and fragrant.
Add the bomba rice to the pan and stir for 1 minute to ensure each grain is well-coated with the tomato and oil base.
Pour in the saffron-infused seafood stock and season with sea salt and black pepper; bring the mixture to a gentle boil.
Reduce the heat to low and arrange the shrimp, mussels, and squid rings evenly over the rice.
Simmer undisturbed for 15-18 minutes until the liquid is fully absorbed, the rice is tender, and the mussels have opened.
Remove from heat and let the paella rest for 5 minutes before garnishing with fresh parsley and serving with a lemon wedge.