Can I make this without store-bought nigiri?
Yes. Use leftover sushi rice (about 1 cup), flatten it in a hot oiled skillet until golden, then top with spicy tuna mixture. Skip the step of disassembling nigiri.
How do I keep the rice crispy if making ahead?
Pan-fry the rice up to 2 hours before serving and store at room temperature. Add toppings just before eating to prevent sogginess.
What can I use instead of Japanese mayonnaise?
Regular mayo works; use 2 tbsp mayo + a pinch of sugar and rice vinegar to mimic Japanese mayo's slight sweetness.
Is this gluten-free?
Check your sriracha label—most brands are gluten-free, but some contain wheat. Use tamari or certified gluten-free sriracha if needed.
Can I scale this for a party?
Yes. Pan-fry the rice in batches (don't overcrowd the skillet), then assemble all portions at once just before serving.