1. In a large, deep, heavy skillet, heat the olive oil. Add the onion and cook over moderate heat until softened, about 1 minute.
2. Add the orange zest, fennel seed, crushed red pepper and cook another 30 seconds, stirring constantly. Add the tomatoes and cook until sauce simmers. Add the tomato paste, a sprinkling of salt and pepper, basil and garlic and simmer another 2 minutes.
3. While the sauce is simmering, cut the scallops in half or quarters, depending on the size of the scallops. Add the scallops to the simmering sauce and cook until the scallops are barely firm, about 2 to 3 minutes. Transfer the cooked scallops with a slotted spoon to a serving bowl.
4. Bring the sauce in the pan to a boil and boil vigorously for 2 minutes.
5. Meanwhile, whisk the starch with the cream until smooth. Whisk into the boiling sauce and return to a simmer. Pour this sauce over the scallops.