1 slab of raw sushi-grade tuna OR 1 package (about 1 cup) of preground raw tuna belly - sometimes Japanese markets have these. If you can't buy sushi-grade tuna near you, order it from Catalina Offshore Products .
2 scallions, finely chopped
2 tablespoons mayonnaise (use Kewpie if you can find it, if not, regular mayo is fine)
Chili oil or Sriracha sauce to taste - add 1/4 tsp at a time until you reach your desired heat level