Store steak in an airtight container in the refrigerator up to 3 days.
Reheat in a skillet coated with olive oil over medium heat. Flip after a few minutes to heat through.
Slice steaks to 1/4 inch thickness.
Add olive oil to a skillet with peppers and onions. Cook over medium heat, stirring often until vegetables are softened, about 8 -10 minutes. Remove from heat.
Meanwhile, combine the tomato sauce, brown sugar herbs, spices, salt and pepper in a bowl. Set aside.
Lay steaks flat on a rimmed sheet pan.
Spoon about 2 -3 tablespoons marinara sauce over steaks and spread evenly.
Top with sautéed vegetables and mushroom slices.
Starting from the narrow end, carefully roll up the steaks.
Tie with butcher twine on each end of the roll.
Repeat with remaining ingredients.
Grill steaks over indirect fire with the grill closed about 25 -30 minutes or until steaks have reached desired doneness using a digital thermometer.
Remove steak to a rimmed baking sheet.
Top with sliced fresh mozzarella cheese.
Broil for about 3 minutes or until cheese is melted.
Spoon about 1 - 2 tablespoons of marinara sauce over cheese.
Garnish with parsley.
Rest steaks for about 5 minutes.
Slice into 1/2 inch slices and serve immediately.