1. Combine 1/2 c. yogurt, ginger and garlic in small bowl. Place beef steaks and yogurt mixture in food-safe plastic bag; turn steaks to coat. Close bag securely and marinate in refrigerator 6 hr. or as long as overnight, turning occasionally. 2. Meanwhile line a strainer with paper towels; set over small bowl. Place remaining 1 c. yogurt in strainer. Cover; let drain in refrigerator 30 min. or as long as overnight to thicken. 3. Remove steaks from marinade; discard marinade. Place steaks on grid over medium, ash-covered coals. Grill, covered, 10-12 min. (over medium heat on preheated gas grill, times remain the same) for medium rare (145°F) doneness, turning occasionally. (Do not overcook.) 4. Meanwhile combine thickened yogurt and wasabi paste. Set aside. 5. Carve steaks into thin slices; season with salt and pepper, as desired. Serve with wasabi-yogurt mixture.
* 2 Tbsp. prepared horseradish may be substituted for wasabi paste.