How to Make It
In a medium saucepan, bring the fish stock to a simmer. Transfer 1 cup of the hot cooking liquid to a measuring cup and crumble in the saffron. Add the fava beans to the remaining stock and cook over moderate heat until bright green, about 1 minute. Using a slotted spoon, transfer the favas to a plate. Squeeze the beans out of their tough outer skins. Cover the remaining stock; keep warm over low heat.
In a large, deep skillet, heat the olive oil. Add the chopped onion and cook over moderate heat, stirring occasionally, until softened, about 7 minutes. Add the fregola and cook over moderately high heat, stirring frequently, until it is well coated with the oil, about 2 minutes. Add the clams, mussels and 1 cup of the hot stock and stir constantly until the shellfish start to open, about 4 minutes; discard any clams or mussels that don't open.
Add the sherry and simmer until reduced by half, about 3 minutes. Stir in the fava beans, sliced red and green bell peppers, plum tomatoes, sun-dried tomatoes, thyme, bay leaves and rosemary. Add the remaining 2 cups of hot fish stock and the saffron-infused stock to the fregola. Lower the heat to moderate and cook, stirring frequently, until the fregola is just tender, about 10 minutes.
Add the shrimp, squid and monkfish to the fregola and cook over moderate heat, stirring a few times, until the seafood is just cooked through, about 5 minutes. Discard the bay leaves and thyme and rosemary sprigs. Stir in the dill and season with salt and pepper. Serve the paella immediately in shallow bowls.
Fregola, the toasted pearl-size Sardinian pasta that is quite similar to couscous, is available at specialty food shops and some supermarkets.