Grilled Chicken Sandwiches With Onions and Peppers

1/4 c balsamic vinegar
1/4 c olive oil
2 cloves garlic, minced
1 t dried rosemary, crumbled
2-4 boneless, skinless chicken breast halvescut in 1”-thick strips
1 medium red onion, sliced
1 green bell pepper,
2-4 crusty sandwich rolls
mayonnaise
romaine lettuce leaves

In a medium bowl, combine vinegar, oil, garlic and rosemary. Marinate chicken in this mixture at least 30 minutes. Prepare grill by covering part of it with aluminum foil. Pierce foil in numerous places and spray with nonstick cooking spray. Grill vegetables on the foil, and chicken on uncovered part of grill over medium heat until cooked through. Serve chicken and vegetables on a crusty sandwich roll along with mayonnaise and lettuce. Makes 2 or 4.