In large bowl whisk together lemon juice, olive oil, sesame seeds and salt and pepper. Add watercress, orange segments and avocados and toss gently to mix. Set aside.
In large skillet over high heat, heat oil until hot. Add tuna portions and sear quickly, about 30 seconds. Trn and sear second side about 30 seconds. Cut each portion into 3 slices. Arrange on plate and top with watercress salad.
B&W Gourmet Farms