Grilled Tuna Salad with Wasabi Dressing

Prepare a bed of coals or heat a griddle or heavy skillet over very high heat until very hot. Brush tuna on both sides with some of the oil. Brush barbecue grill or griddle with oil; cook tuna 2-3 minutes on each side until browned on outside, but still very rare in center. Cool tuna briefly then cut it in 1-inch squares. Combine tune, tomatoes, peppers, onion and thyme. Set aside. Combine garlic, remaining oil, vinegar, mustard, mustard seeds, and Worcestershire sauce; whisk to blend, season with salt and pepper. To serve, line a platter or 4 individual plates with lettuce. Fold dressing into tuna mixture; then arrange salad on platter or individual plates. Makes 4 servings.