Use grill or non-stick skillet and heat to high. Brush tuna with oil and season with salt and pepper. Add tuna and sear for 2-3 minutes each side, turning once. Transfer to cutting board and slice in ½ -inch thick slices.
In large bowl, toss butter lettuce with ¼ cup Marie’s Poppy Seed Dressing. Divide greens onto 2 plates and top each salad with orange segments, avocado and sliced tuna. Drizzle remaining Marie’s Poppy Seed Dressing across top of salad to serve.