Ready In: 20 mins
Prep: 15 mins
Cook: 5 mins
Yields: 8 Servings
In a small bowl, stir together the yogurt, blue cheese, lemon juice, olive oil, mustard and 1/4 teaspoon each of the salt and black pepper; set aside.
Heat gas grill or grill pan to medium-high heat; sprinkle steaks with remaining 1/4 teaspoon salt and pepper.
Chop lettuce into 1-inch pieces and transfer to a large bowl.
Grill steak for about 2 to 3 minutes per side, or until meat registers 130°on an instant read thermometer for medium-rare. Remove steak to a cutting board and tent with foil; let rest 5 minutes.
Toss lettuce with reserved dressing and divide salad equally among four plates. Thinly slice steak against the grain, then divide steak evenly among plates. Serve immediately.