4 teaspoons olive oil, divided |
1/2 teaspoon salt, divided |
1 1/4 lbs chicken breast tenders |
1/2 cup balsamic vinegar, divided |
2 cups red bell peppers, cut into strips (about 2 medium) |
2 cups onions, vertically sliced (about 1 large) |
16 ounces focaccia bread (2 8oz loaves) |
4 ounces provolone cheese, thinly sliced |
1/8 teaspoon black pepper |