Preheat oven to 450.
Mix Rub ingredients together.
Take your sea bass and pat dry with a paper towel; leave the skin on.
Sprinkle a generous amount (about a teaspoon or two) of the rub on the top of the filet.
Add purple cabbage to a small mixing bowl and add your grapeseed oil and kosher salt. Mix well.
Mix your Sriracha Mayo ingredients together, testing until you get your perfect amount of spiciness.
Bake your fish for 4-6 minutes per 1/2 inch thickness and the cabbage requires about 4-6 minutes as well.
Place fish, skin-side down, on a foil-lined baking sheet along with the cabbage, or add cabbage later for a thicker piece of fish.
Toast Hamburger bun until lightly browned.
Remove salmon, cabbage, and bun from the oven. Take the bottom of the bun and spread as much sriracha mayo as you desire. Add purple cabbage on top.
Take a spatula and lift the fish fillet off of its skin, which should stick to the foil, and place on top of the cabbage.
Add arugula and top of the bun. Enjoy!