Heat the olive oil in a paella pan or wide heavy-bottomed skillet over medium heat.
Add the diced chorizo and sauté for 2-3 minutes until the smoky oils are released and the edges are crisp.
Add the shrimp to the pan and sear for 1 minute per side until just pink, then remove the shrimp and chorizo and set them aside.
In the same pan, sauté the onion, garlic, and red bell pepper until the vegetables are softened and fragrant.
Stir in the Bomba rice and smoked paprika, stirring for 1 minute to toast the grains and coat them in the oils.
Crumble the saffron threads into the seafood broth and pour the mixture into the pan; season with sea salt and black pepper.
Bring to a gentle simmer and cook undisturbed for 10-12 minutes until the liquid is mostly absorbed and the rice is nearly tender.
Nestle the seared shrimp, chorizo, cleaned mussels, and frozen peas into the rice.
Cover the pan with a lid or foil and cook for an additional 5 minutes until the mussels have opened and the shrimp are fully opaque.
Remove from heat and let the paella rest for 2 minutes before garnishing with fresh parsley and a lemon slice.