Step 1Cook the onions in the butter in a 4-quart saucepan over medium heat until tender, about 5 minutes. Remove from the pan; set aside.
Step 2Spray the saucepan with nonstick cooking spray. Add the turkey and cook, stirring occasionally, until the turkey is no longer red, about 5 minutes.
Step 3Stir in the celery, bell pepper, brown sugar, salt, Worcestershire sauce, chili sauce and vinegar. Bring to a simmer, cover and cook 30 minutes, stirring occasionally.