Slice the bread open lengthwise and then cut into sandwich size.
Season the chicken breasts with theground cumin and salt and pepper,and grill on both sides until cooked through. Let cool slightly, then slice into thin strips.
Saute the frozen peppers and onions with some salt and pepperfor about 3-5 minutes, or until the water has cooked off and they begin to caramelize.
To assemble, spread the salsa on the bottom of the bread. Add the grilled chicken slices, the sauted peppers and onions, then top with a slice of cheese.
Microwave or put under the broiler to melt the cheese, if necessary.
Serve Chicken Fajita Sandwiches with fresh fruit.