1 1/2 pounds boneless, skinless turkey breast (about half of a whole turkey breast)
1 tablespoon balsamic vinegar
4 peach halves (preferably fresh) or pineapple spears
Combine first 7 ingredients and set aside 3 tablespoons of the mixture.
Add onions and turkey breast to remaining mixture, place in a shallow bowl or zip lock bag, and marinate 1 to 4 hours, turning several times.
To grill:
Remove turkey breast from marinade and grill over medium high heat 12 to 15 minutes per side or until internal temperature reaches 165°.
Add balsamic vinegar to reserved marinade and place 1 tablespoon in the hollow of each peach half. Grill over medium heat for last 10 minutes.
To roast:
Preheat oven to 400°.
Place turkey on broiler pan in center of oven and roast for 20 minutes or until internal temperature reaches 165°. Add balsamic vinegar to reserved marinade and place 1 tablespoon in the hollow of each peach half. Put in oven with turkey the last 10 minutes.
Serving:
Remove turkey breast from heat and let rest 5 minutes before slicing.