In a small mixing bowl, combine the brown sugar, salt, paprika, garlic powder, and cayenne pepper. Press the mixture generously on both sides of the skirt steak. Let sit at room temperature while preparing the grill.

Prepare the grill for direct heat. Brush the grill grates with oil.

Pat the steak dry and grill for 2-3 minutes per side for medium rare. Cover the steak with foil and let sit for 10 minutes before slicing.

If using a grill pan, heat the pan until it is screaming hot, do not oil the pan, and grill as above.