Heat the olive oil in a large, wide skillet or paella pan over medium heat. Add the chopped onion and red bell pepper, sauteing until they are softened and translucent, about 5-7 minutes.

Stir in the minced garlic, smoked paprika, and saffron threads. Cook for about 1 minute until highly fragrant, being careful not to let the garlic burn.

Pour in the short-grain rice and stir well to coat the grains in the oil and spices. Let the rice toast slightly in the pan for 2 minutes.

Deglaze the pan with the white wine, scraping up any browned bits from the bottom. Simmer for 2 minutes until the liquid has mostly evaporated.

Pour in the broth, season with salt and black pepper, and bring the mixture to a gentle boil. Reduce the heat to low, cover, and let simmer undisturbed for 15 minutes.

Uncover the skillet and arrange the shrimp and mussels evenly over the rice. Scatter the frozen peas on top, cover again, and cook for another 8-10 minutes.

Check that the shrimp are pink and opaque, the mussels have opened, and the rice has absorbed the liquid. Discard any mussels that remain closed, remove the pan from heat, and let it rest for 5 minutes.

Garnish with fresh parsley if desired and serve hot straight from the skillet with lemon wedges on the side for squeezing.