Using a pizza cutter, cut tortillas into 4 equal triangles. Brush with oil and sprinkle with salt. Arrange tortilla triangles in a single layer on baking sheets and place them in the oven for 10 to 15 minutes, or until golden brown and crispy.
Thaw tuna, if frozen, rinse with cool water and pat dry with paper towels. Coat the tuna steaks with soy sauce, lime juice, and garlic, cover tightly, and refrigerate for 15 to 30 minutes.
Heat a non-stick skillet over medium-high heat. When the pan is hot, remove the tuna steaks from the marinade and sear them for 2 to 3 minutes on each side (even a little longer if you want the tuna less rare than pictured).
Remove from pan and slice into 1/4-inch thick slices.
Cut the avocado in half. Twist to pull apart and remove the pit. Scoop out the flesh. Place in a medium bowl and mash the avocado with a fork leaving some chunks.
Add the garlic, onion, and salt. Squeeze the lime juice over all the ingredients and give everything a gentle stir, but don’t overdo it.
Place tuna slices on baked flour tortilla chips, drizzle with Sriracha sauce, crema Mexican, top with a jalapeño slice, and garnish with cilantro.
This dish can be served as an elegant appetizer or as a light meal.