Place steaks in a large, resealable plastic bag. Add teriyaki sauce. Seal bag and turn to coat; refrigerate overnight.
In a bowl, combine cucumber, sour cream, mayonnaise, chives, dill, and salt. Cover and place in refrigerator.
Drain and discard marinade. Grill steaks, uncovered, over medium-high heat for four to five minutes on each side. Serve with cucumber sauce.
Yield: Four servings.