Bring a large pot of water to boil. Place the oil in a wide pot (about 12” wide) set over medium, to medium-high heat. Add the onion and cook 4 minutes. Mix in the wine, stock, diced tomatoes and tomato paste, and bring to a simmer.
Meanwhile, cook the pasta in the boiling water until tender, about 10 minutes. When the tomato mixture is simmering, mix in the pesto, salt, pepper and cubed fish. Simmer 2 minutes, and then add the mussels and prawns. Cover and cook until the mussels open and the fish is cooked, about 3 to 4 minutes.
When the pasta is cooked, drain it well and toss into the tomato/seafood mixture. Spoon into serving bowls and enjoy
Note: Cooked, peeled prawns are available in our seafood department. Rinse the mussels in cold water before using and remove any beard-like material. Discard mussels that do not close when squeezed before cooking, or that do not open after cooking. Both are signs the bivalve was dead before cooking it and should not be eaten.