Preparation Cook chopped bacon in a 2-quart heavy saucepan over moderately high heat, stirring occasionally, until crisp, about 2 minutes. Transfer bacon with a slotted spoon to paper towels to drain. Add onions and potato to fat in pan and cook over moderately high heat, stirring frequently, until onions are thawed, about 1 minute, then sprinkle in flour and cook, stirring, 1 minute. Slowly whisk in milk and bring to a boil, whisking constantly. Add vegetables, thyme, salt, and pepper and simmer, uncovered, stirring occasionally, 3 minutes. Cut scallops in half (or quarters if large) and add to soup, then simmer just until scallops are cooked through, about 3 minutes. Discard thyme sprig (if using), then season soup with salt and sprinkle with bacon.
Preparation Cook chopped bacon in a 2-quart heavy saucepan over moderately high heat, stirring occasionally, until crisp, about 2 minutes. Transfer bacon with a slotted spoon to paper towels to drain. Add onions and potato to fat in pan and cook over moderately high heat, stirring frequently, until onions are thawed, about 1 minute, then sprinkle in flour and cook, stirring, 1 minute. Slowly whisk in milk and bring to a boil, whisking constantly. Add vegetables, thyme, salt, and pepper and simmer, uncovered, stirring occasionally, 3 minutes. Cut scallops in half (or quarters if large) and add to soup, then simmer just until scallops are cooked through, about 3 minutes. Discard thyme sprig (if using), then season soup with salt and sprinkle with bacon.