Pour the chicken broth into a microwave-safe container and heat on high for 3 minutes until hot. Stir in the saffron strands and set aside.
Pat the shrimp dry with paper towels on a cutting board. Season both sides with 1 teaspoon of salt and the pepper, then set aside.
In a 12-inch cast-iron skillet, heat the olive oil over medium-high heat until shimmering. Add the chorizo and cook, stirring occasionally, until browned in some areas, about 3 minutes. Add the onion and cook until it becomes soft, about 3 minutes. Stir in the garlic and paprika and cook until fragrant, about 30 seconds. Add the rice and stir for about 1 minute until lightly toasted.
Stir in the tomatoes and the prepared chicken broth. Combine well and reduce the heat to low. Cover the pan with a lid and cook without stirring for 15 minutes until the rice is al dente.
Remove the lid and arrange the shrimp, mussels, and peas on top of the rice. Cover again and increase the heat to medium-high. Cook for about 5 minutes until the shrimp turn opaque and the mussels open. Discard any mussels that remain closed.
Remove the lid, drizzle the lemon juice over the paella, sprinkle with the remaining teaspoon of salt, and garnish with parsley. Serve immediately. Enjoy!