Sprinkle salt in a large cast-iron skillet over medium-high heat. Add steaks; sauté 2 minutes on each side. Remove from pan. Add garlic; sauté 30 seconds. Add sherry; boil 30 seconds, scraping skillet to loosen browned bits. Return steaks to pan; cook 2 minutes. Add soy sauce and pepper. Remove steaks to serving plates. Remove pan from heat; stir butter into sherry mixture until blended. Divide sauce evenly over steaks. Top each steak with 3/4 teaspoon ginger, if desired.