1. Heat a large nonstick skillet over medium-high heat; add ham steak. Cook 3 minutes on each side or until browned. Remove from pan, and keep warm.
2. Melt 1 tablespoon butter in pan over medium-high heat. Add onion and garlic; sauté 3 minutes. Add half of mustard greens; cover and cook 2 minutes or until slightly wilted. Add remaining greens and 1/2 cup cider. Cover and cook 15 minutes, stirring occasionally. Stir in salt and pepper.
3. While greens cook, bring remaining 1 cup cider to a boil in a small saucepan. Cook 10 minutes or until reduced to 1/4 cup. Remove from heat, and stir in remaining 1 teaspoon butter.
4. Divide wilted greens evenly among 4 plates. Cut ham steak into 4 pieces, and place over greens. Drizzle cider sauce over ham and greens.