Rinse 1 cup of sushi rice under cold water until the water runs clear. Cook according to package instructions until done, about 20 minutes. Transfer to a bowl and gently fold in 2 tablespoons rice vinegar, 1 tablespoon granulated sugar, and 1 teaspoon kosher salt while still warm.

Transfer the seasoned rice to a lined container, spreading it evenly into about 1-inch thickness. Press down firmly and refrigerate for at least 3 hours or overnight.

Finely chop 8 ounces of sushi-grade ahi tuna and mix in a bowl with 2 finely chopped scallions and 3 tablespoons of spicy mayo. Set aside in the refrigerator.

Cut the chilled rice into 2x2 inch pieces. Heat grapeseed oil in a skillet over medium-high heat until shimmering, about 350°F. Fry the rice pieces until golden brown and crispy, about 2 minutes on each side.

Place fried rice bites on a platter. Top with the spicy tuna mix, sprinkle with black sesame seeds and garnish with jalapeño. Serve immediately.