Take a gas grill and heat it to medium-high heat.
Boil the chicken stock in a medium saucepan. Add saffron and salt to it.
Remove the saucepan from heat and let it rest for about 15 minutes.
Now, heat oil over medium heat in a 12-14 inch stainless steel skillet.
Add onion and red pepper to it. Cook for 5 to 7minutes. Then, add chorizo and garlic to it and stir.
Set the skillet with the sofrito on the gas grill. Now, add rice, infused stock, peas, salt, tomatoes, shrimp, mussels, and clams to it.
Now, add rice to the skillet and cook by stirring for 4 to 5 minutes.
Close the cover of the grill and simmer rice for 15 minutes.
Pour about 1 cup of hot water if the mixture looks dry.
Settle the mussels and clams into the rice. Keep hinge sides up so they release their juices into the rice.
Arrange the shrimp around the shellfish.
Take the pan and cover it with foil. Cook it for 6-10 minutes until shrimp and rice are cooked. Also, make sure mussels and clams have opened.
Garnish it with parsley and serve.