Brush tuna steaks with olive oil, and sprinkle with salt and pepper. Place the tuna steaks in a very hot sauté pan and cook for only one minute on each side. Set aside on a platter. Meanwhile, in a small bowl, combine 4 tbsp olive oil, salt, pepper, lime zest of 2 limes, 1 tsp wasabi, 6 tbsp freshly squeezed lime juice, 2 tsp soy sauce and 10 dashes Tabasco. Add 2 avocados diced to the vinaigrette. Cut the tuna in chunks and place it in a large bowl. Add ¼ c. minced scallions and ¼ c. diced red onion and mix well. Pour the vinaigrette mixture over the tuna and carefully mix.