In a medium saucepan, gently saute onion, celery, carrot, and garlic until soft. Add crab shells, stir and deglaze with wine and reduce. Add saffron and tomatoes, reduce. Add 2 liters cold water and bring mixture to a boil. Skim off the fat and simmer for 45 minutes, continuing to skim occasionally. Add basil and let cool. Strain and season with sea salt.
In a small sauce pan gently cook capsicum and capers. Add onion half, bay leaf, and garlic and chili. Cook gently for 15 minutes. Add freshly chopped parsley and tomatoes, bring mixture to a simmer for 15 minutes. Add olives and continue to cook for another 15 minutes. Add sugar and salt to desired taste. Add basil leaves and allow set aside to cool.
Zuppa Di Pesce Aua "Cagliaritana":
Cook the fregola in crab stock until tender and liquid has been absorbed. Place the sauce back onto medium-high heat and add the seafood. Gently poach until seafood is cooked. Place the fregola to 1 side and divide seafood among with sauce onto the fregola and sprinkle with a little chopped parsley. Serve hot.
This recipe was provided by professional chefs and has been scaled down from a bulk recipe provided by a restaurant. The Food Network Kitchens chefs have not tested this recipe, in the proportions indicated, and therefore, we cannot make any representation as to the results.