Mix all ingredients for blackening seasoning in sealed container. Makes enough for 2 or 3 batches. Store leftovers for future use.
Prepare lime cream sauce by combining all ingredients. Allow to chill in the refrigerator for about an hour for flavours to combine. Will keep for several days.
Prepare slaw by combining all ingredients. Allow to chill in the refirgerator for about an hour. Reserve extra cilantro and parsley for garnish. Will keep for several days.
Clean fish, remove any bones and cut into 1-2 inch by 3-4 inch pieces. Lay in one layer on a large plate or platter. Sprinkle blackening seasoning generously over top. Turn pieces and sprinkle other side.
Heat cast iron pan until starting to smoke. Add 1 Tbsp butter and tilt to cover pan. Add half of the pieces quickly to the hot pan. Cook until pieces are very dark, about 1-2 minutes depending on the thickness. Turn and cook until other side is equally blackened.
Remove to warm serving plate. Place in warm oven if desired while cooking second batch.
Once pan has returned to high heat, add second Tbsp of butter and cook remaining pieces until blackened on both sides.
If desired, grill tortillas slightly before assembling tacos to add a bit of char and soften.
Place 2 - 3 pieces of fish into tortilla shells. Top with generous amount of slaw then drizzle lime cream sauce over top. Garnish with fresh cilantro or parsley and pickled jalapenos.