At least 4 hours before you intend to cook this dish, marinate chicken breast in a mixture of 2 Tbsp Olive Oil, 1 tsp Balsamic Vinegar, 1 tsp Italian seasoning, 1/2 tsp ground sage and 1/8 tsp pepper (increase amount of marinade if using more than 1 chicken breast - I used one cut into 3 pieces).
Broil for 10 minutes on each side using a double broiler. If you do not have a double broiler, you can us a make-shift one by placing a pan of water on a rack directly under the top rack of your stove. I put aluminum foil on the top rack to know where to place the chicken as to be directly over the pan of water.
Top with 2-4 slices of tomato and 1/4 cup feta cheese. Broil until cheese starts to melt and turns golden brown. If using the make-shift double broiler, place chicken on a cookie sheet before topping with cheese.