Add oil, sugar, vinegar, soy sauce, garlic, and pepper to a gallon sized ziplocking bag. Squeeze together to evenly combine.
2 tbsp extra virgin olive oil, 2 tbsp brown sugar, 1/4 cup balsamic vinegar, 1 tbsp soy sauce, 4 cloves garlic, pepper
Add the chicken to the bag. Seal, squeezing the excess air out as you do. Chill in the refrigerator for at least 30 minutes, or up to 8 hours, flipping the bag over occasionally.
6 boneless, skinless chicken thighs
Set a large skillet over medium heat. When hot carefully add the chicken to the skillet. Cook until nicely browned on both sides and cooked through, roughly 5-7 minutes per side. Transfer the cooked chicken to a waiting plate
Add the rest of the marinade to the skillet and bring the mixture to a simmer over medium heat. Stir it often until it's reduced and the sauce has thickened.
Reduce the heat to medium low and return the chicken to the skillet. Spoon the glaze over top of the chicken.
Top each piece of chicken with a slice of cheese, cover, and let rest just until the cheese has melted some. Remove the skillet from heat.
6 thick slices fresh mozzarella cheese
Top each piece with two slices of tomato, serve warm, and enjoy!
2 ripe roma tomatoes