Seared Tuna Steaks with Wasabi Green Onion Mayonnaise

Name: Seared Tuna Steaks with Wasabi-Green Onion Mayonnaise
Ingredients: 1/2 cup mayonnaise; 2 tablespoons minced green onions (white and green parts); 1 teaspoon (or more) wasabi paste; 2 tablespoons teriyaki sauce; 1 tablespoon soy sauce; 1 tablespoon unseasoned rice vinegar; 4 8-ounce tuna steaks (preferably ahi; each about 1 inch thick); Vegetable oil