In a small bowl combine mayonnaise, chile paste, hot chile oil, and sesame oil and stir to combine.

Place 1 piece of toasted seaweed on top of a sushi roller (makisushi), with the short end closest to you. Using lightly wet fingers, press enough rice onto the seaweed to completely cover the seaweed, and press firmly so that rice adheres to seaweed. Turn seaweed over so that rice side now faces down. Arrange strips of tuna on top of seaweed, with the tuna strips running vertically in line with the short side of the seaweed, about 1/3 of the way into the seaweed sheet.

Spread a small amount of wasabi on the tuna, then sprinkle with sliced scallions. Using the sushi roller as a guide, carefully begin rolling the seaweed up, pressing as tightly as possible so that the roll is firm and compact. Once the roll is completely rolled, reposition roll on sushi roller and press again. Sprinkle sesame seeds on a flat surface and lightly roll in seeds to coat. Allow roll to sit for a few seconds before slicing with a sharp, damp knife.

Cut roll into 6 or 8 pieces and serve with dollops of sauce spooned on top, or alongside for dipping. Repeat with remaining ingredients.

In a large bowl, add rice and cover with lots of water. Stir rice in water with your hands, then pour off most of the water, and agitate 10 to 15 times by quickly moving your hand back and forth, swishing rice against side of bowl. Rinse the rice several more times, until the water that drains off of the rice is almost clear. Transfer the rice to a colander and let drain for 1 hour, undisturbed. Transfer the rice to a rice cooker, add the water, cover and cook as directed by manufacturer's directions.

While the rice is cooking, bring rice vinegar to a boil in a small saucepan, and then remove from the heat. Add sugar and salt and stir until dissolved. Allow to cool to room temperature.

When rice is done, allow cooked rice to remain in rice cooker for 10 minutes. Transfer rice to a large shallow mixing bowl (traditionally a wooden tub, called a hangiri), so that rice forms a mound in the center of the bowl. Using a diagonal slicing motion, gently cut into rice with a wooden paddle (called a kijakushi), and pour cooled vinegar mixture over top of rice. "Cut" rice several times to evenly distribute vinegar mixture, then allow to cool. Gently turn rice over from time to time with paddle so that rice cools evenly. You might want to consider using a fan if time is of the essence. When rice has cooled to body temperature, it is ready to use for sushi rolls. Rice can be kept at the proper temperature by placing it in an insulated container such as a small ice chest, covered with a damp kitchen towel.

Yield: enough rice for at least 7 large rolls (futomaki)