Pat steaks dry with paper towels, then scatter the chile rub over the steaks, patting it in with your fingers. (Be sure to wash your hands well when finished with the rub, to remove all chile powder from your fingers.) Let the meat rest at room temperature as you heat the grill.
Oil a grill rack and arrange 4 to 5 inches from heat. Prepare grill for a hot fire (high temperature).
Grill steaks until darkly crusted, 3 to 4 minutes per side. Reduce heat to medium low (on a gas grill) or move steaks to low-heat area (for a charcoal grill), cover and grill for another 3 to 4 minutes for medium-rare to medium (135 degrees to 140 degrees).
Transfer to a platter, cover loosely with foil, and let rest for 5 to 8 minutes. Serve topped with generous dollops of Salsa Butter.
Nutrition information per serving using 2 tablespoons salsa and half the rub:
Calories431Fat20 gSodium1,470 mg