Heat olive oil in a paella pan or wide skillet over medium heat.
Sauté the chorizo until the fat renders and it becomes slightly crisp.
Add the onion and bell pepper, cooking until softened and fragrant.
Stir in the garlic, smoked paprika, and tomato puree, cooking for 2 minutes.
Add the rice and stir to coat every grain in the aromatic oil and spices.
Pour in the seafood broth and saffron, then season with salt and pepper.
Bring to a simmer, then reduce heat to low and cook undisturbed for 10 minutes.
Nestle the shrimp and mussels into the rice, cooking for another 5-7 minutes until seafood is cooked and liquid is absorbed.
Let the paella rest for 5 minutes to develop the 'socarrat' crust before garnishing with parsley and lemon.