In a small bowl whisk together sour cream, milk, lime juice, hot sauce, taco seasoning and salt. Cream should be thin enough to drizzle. Set aside.
Heat a skillet to medium heat. Swirl the pan with canola oil.
Pat the halibut dry with a paper towel. Season both sides generously with taco seasoning, salt and pepper. Place into hot skillet and cook until browned on both sides and cooked through, being careful not to overcook and dry out. Halibut is cooked when it flakes with a fork, but is still moist inside. Flake halibut apart in pan.
Steam corn tortillas in a tortilla warmer or ziploc bag in microwave for 2 minutes.
!To Assemble Tacos:
Take two steamed corn tortillas and place some cooked halibut in the center. Top halibut with cabbage, and a generous amount of cilantro and green onion. Top with an avocado slice and drizzle with crema. Serve with salsa and lemon/lime wedges on the side.