I sometimes feel like eating spicy tuna, my husband as well. When we fell like that, I get nice piece of tuna fillet and chop it and make spicy tuna.
I usually like to eat putting on steamed rice and make a spicy tuna bowl; "Donburi" style.
Fresh chopped tuna with little mayonnaise, green onion, Japanese chili pepper, and chili oil.
Great thing to make this yourself, you can adjust the spiciness as much as, or as less as you want and make perfect spicy tuna every time. I barely order spicy dish from any restaurant until I know the taste, because you never know how spicy that dish is ;)
I added little ground white sesame seed, and matched up with clear soup.