In a large bowl, mix together the ground turkey, bread crumbs, lemon zest, lemon juice, thyme, salt, and pepper. Form into two (2) patties the same size as the bread you are serving it on, place on a plate, cover with plastic wrap, and refrigerate until ready to grill.
In a large frying pan with olive oil, sautonion until almost caramelized. Add bell pepper and sauttill heated through and softened. Sprinkle with a little salt and pepper. Remove from heat and set aside.
Preheat barbecue grill; brush and oil the grates. Grill turkey patties approximately 5 to 6 minutes on each side or until internal temperature reaches 165 degrees F. on your meat thermometer. Top each turkey patty with cheese slices during the last few minutes of cooking to melt.
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While the turkey patties are cooking, cut open the bread the size you want for this open face sandwich, then cut in half for two servings, and butter each half. Grill bread slices, opened end down to form grill marks, or toast in toaster.
Place one turkey burger on each grilled bread slice. Place tomato slices on top of the melted cheese, then arrange grilled red pepper pieces, and then grilled red onion slices over the top. At this point you can add any condiments you desire.
Serve with a colorful green salad dressed with vinaigrette of your choice.
Makes 2 large Open-Face Sandwiches.