Cook the Sushi Rice and mix in measure of Rice Vinegar and salt.
In a separate bowl, mix together the tuna, Wasabi Mayo, and Sesame Seeds.
Mould the onigiri with the tuna mixture in the middle (use an onigiri mould for easy shaping, or shape by hand using damp, salted palms to form a triangle around the filling).
Cut the Nori Sheets into long strands, using the onigiri mould to find the approximate height, and then trim the zig zag pattern.
Wrap the Nori Sheet around the bottom of the onigiri to form the mountain shape.
Decorate the mountains with togarashi seasoning to create your lava effect.