Preheat the oven to 275 degrees . Wrap up the tortillas in a damp kitchen towel, set them into a pie plate or cake pan and place in the oven.
In a small bowl, combine the grill seasoning, cumin, paprika and chili powder. Rub the mixture on both sides of the tuna steaks.
In a large skillet, heat 2 tablespoons oil over medium-high heat until the oil ripples. Add the cabbage and cook, turning with tongs occasionally, until just tender, about 5 minutes. Add a few tablespoons water to help wilt, if needed. Toss in the scallions until combined; season with salt to taste. Turn off the heat and cover to keep warm.
In a second large skillet, griddle or grill pan, sear the tuna steaks for 2 minutes on each side for rare, or up to 5 minutes on each side for well-done. Cut into thin slices.
Using a food processor, mix the avocados, cream and lime juice until smooth. Season the avocado cream with salt and hot sauce to taste.
Remove the tortillas from the oven. Place sliced tuna and cabbage on each tortilla and fold over; serve the avocado cream on the side.