Wash and drain your rice, then cook it according to your preferred method. While the rice is still hot, mix together the rice vinegar, sugar, and salt until dissolved, then fold the mixture into the rice. Set aside to cool slightly.

In a bowl, combine the diced salmon or tuna, mayo, soy sauce, sriracha, sesame oil, lime juice, green onion, and a pinch of salt. Cover and refrigerate until ready to use.

Whisk together the mayo, rice vinegar, sriracha, sugar, and a pinch of salt for the spicy mayo. Taste and adjust to your liking, then set aside.

Cut your nori sheets into large circles (you can use a medium plate or tortilla as a stencil if you have one handy). In a shallow bowl, whisk together the cornstarch, flour, and water to make a smooth batter. In a separate bowl, mix the panko breadcrumbs with salt, garlic powder, smoked paprika, and a few cracks of black pepper.

Press a thin, even layer of sushi rice onto one side of each nori circle. Brush the other side with the flour batter, then press it firmly into the seasoned panko breadcrumbs so they stick well.

Heat a thin layer of avocado oil in a pan over medium heat. Place the tacos breadcrumb-side down and shallow fry until golden and crispy. While they're still hot and pliable, gently fold each one into a taco shape and hold for a few seconds.

Fill each taco with the spicy salmon or tuna and top with sliced avocado, sliced cucumbers, a drizzle of spicy mayo and eel sauce, and a sprinkle of sesame seeds.