Preheat oven to broil. In a small bowl, add all seasonings and stir to combine. Cover the fish filets in grapeseed oil (or another high heat oil). Using a spoon, cover all sides of the fish evenly in the seasoning. Broil for 6 minutes or until you reach your desired done-ness.
To prepare the avocado crema, add all ingredients to a blender or a food processor and blend until combined. If your blade is not catching, add a dash of water until the blade catches and can process until smooth.
To assemble the tacos, use a fork to flake the fish. Layer in the blackened halibut, sliced radishes, sliced jalapeños and the avocado crema.