Cut the tuna sashimi into 1-1.5 cm cubes. Cut the green onion in small pieces. Finely chop the garlic.
Add the sesame oil to the tuna, green onion and garlic from Step 1, and mix lightly.
Add all of the seasonings, except the mayonnaise. Adjust the amount of chilli powder and other spices to suit your taste.
Add the fish roe and mix until it's blended into the other ingredients.
Add in the mayonnaise and mix well. Taste, and adjust the seasoning to your liking.
It's done. It looks something like Negitoro (minced fatty tuna and green onion).
Story Behind this Recipe
This is my husband's recipe for Spicy Tuna. After eating this at Genki Sushi in Honolulu, he wondered what was in it, and decided to try making it himself. This is Marc's original recipe, settled on after many revisions.
Be sure to taste and adjust the spices as you go along. It turns out differently depending on this. The taste of sansho Japanese pepper should be subtle, but sansho is a must!