This is how my uncle always cooked tuna or swordfish. I like it with albacore. Good and simple
Tuna steaks(about 1" thick)
2 cups mayonnaise
3 tablespoons horseradish
salt
pepper
garlic powder
Mix together in bowl mayo and horseradish. Add salt pepper and garlic powder to taste. Mix thoroughly.
Add tuna steaks one at a time. Make sure they are completely coated. Let sit refrigerated for about 1/2 hour.
Preheat broiler on high, or have barbeque ready to go. Put steaks on hot grill. If using broiler cook fish without flipping it about 10 minutes. If using bbq, flip after 4-5 minutes to get nice grill marks. Sauce should be browned and a little crispy on outside of fish when done. Fish you caught that day works best as always. Goes good with beer.