In saucepan, heat oil over medium-high heat. Cook turkey, onion, red pepper, chili powder and salt, breaking turkey up with spoon, until turkey is browned and vegetables are softened, 5 or 6 minutes.
Stir in tomato sauce, zucchini, corn, molasses and vinegar; bring to boil. Reduce heat and simmer until thickened, about 5 minutes. Transfer to Thermos. Toast buns, then let cool. Package buns separately to assemble at lunchtime.