Make the Sofrito first. (Can be made a few days ahead and refrigerated.)
To make the sofrito, heat oil in a large saucepan. Add onion, garlic, bay leaf and salt. Cook until onion is soft and translucent. Add red pepper and cook until soft, about 10 minutes, then add tomato and continue to cook, stirring occasionally until mixture is thick and has the consistency of jam, about 20 minutes or more. Remove from heat. (If you're making this the day before, refrigerate the sofrito in a covered container.)
Heat a large (15 inch) skillet or paella pan over medium-high heat. Add ¼ cup oil. When it ripples, add the fish. When it just begins to brown, add the prawns. Cook just until prawns are no longer translucent. Remove to a plate.
Add garlic to the skillet, then sofrito and bay leaves. Cook for 2 minutes. Add rice and stir. Add smoked paprika and saffron. Stir until rice sizzles. De-glaze the pan with the wine, then add the clam nectar or fish stock. Bring to a boil, then add mussels. Cook until they open, then remove to a plate. Discard any that do not open.
Reduce heat to low and simmer rice for 10 - 15 minutes until rice is almost tender. Add seafood back into the skillet, on top of the rice. Increase the heat to medium-high, and cook until a crust has formed on the bottom of the pan. Be patient and resist the urge to stir! Scatter with peas.
Turn off the heat and let sit in the pan for 5 minutes until the peas are heated through. Garnish with parsley and serve.
This recipe makes enough for 4. If you double the recipe, use two skillets or a large paella pan.