Romesco is a traditional Catalan sauce made with pounded nuts and peppers. Here, a derivative of it is used to make a Catalan fish and shellfish stew. Firm fish, such as monkfish, works well in a stew but careful substitutions can be made. Similarly, the shellfish can vary between clams, mussels and prawns, depending upon availability. I’d use less fish stock for mussels or clams, which release their own liquid, than prawns, which do not.
In a deep sauté pan, heat the olive oil over medium heat. Add the onion together with a pinch of salt and cook the onion, stirring occasionally, until golden and sweet (about 15-20 minutes). Then stir in the garlic, rosemary, bay leaves and red peppers. When the red pepper has softened for at least 10 minutes, stir in the paprika and tomatoes and simmer for another 10 minutes. Now add the wine and drive the alcohol for a couple of minutes before adding the fish stock together with the saffron-infused water. Finally, thicken the base with teh ground almonds and taste for seasoning. (You can complete this stage ahead of time.)
When almost ready to eat, reheat the base if necessary and add the fish and shellfish. Put a lid on and simmer until the fish is cooked through and (if appropriate) the shellfish have opened.
This goes well with new potatoes or a raw fennel salad.