Prep the Tuna Mixture: Finely dice the sashimi-grade tuna and place it in a mixing bowl. Add mayonnaise, sriracha (start with 1 teaspoon and adjust to taste), chopped green onion, and finely chopped jalapeño. Drizzle with a splash of sesame oil if using. Gently mix until well combined. Cover and refrigerate while you prep the rest.
Make the Crispy Rice (Optional):
If you're serving with crispy rice, press cooked sushi rice into a flat layer on a parchment-lined tray. Chill for 10-15 minutes to firm up. Cut into small squares.
Air Fryer Method: Lightly spray or brush rice squares with oil and air fry at 400°F for 10-12 minutes, flipping halfway, until golden and crispy.
Stovetop Method: Heat neutral oil in a skillet over medium-high heat. Pan-fry rice squares for 2-3 minutes per side until golden and crisp. Drain on paper towels and sprinkle with a little soy sauce.
Assemble Your Tartare: Spoon the spicy tuna mixture onto your chosen base - crispy rice squares, butter lettuce leaves, or seaweed snacks. Top with extra green onions, a drizzle of sriracha, or sesame seeds if desired.
Serve and Enjoy: Serve immediately for the best flavor and texture. This makes a perfect light meal, appetizer, or build-your-own party platter.