Flat Iron Steak

0 In a wide glass pan, mix the following ingredients: tequila, lime juice, honey, brown sugar, chopped garlic cloves, and cilantro. Blend well.  
1 Salt and pepper the meat, then add it to the marinade. Refrigerate for a couple of hours, turning occasionally.
2 Remove the meat from the glass pan and place the tequila-lime mixture in a small, heavy-bottom pan.  
3 Add the two tablespoons sugar, salt, and pepper. Cook over medium heat until reduced by a third.  10 to 15 minutes.
4 Add the butter to the reduced marinade and swirl over medium heat.  
5 Prepare the grill or heat a grill pan to high heat. Place the meat on the grill and cook until desired doneness is reached.
6 Serve sauce over the sliced meat.