Place one nori sheet horizontally on a bamboo rolling mat, with the rough side facing up.
Wet your fingertips with water and spread ¼ of the prepared sushi rice (about ½ cup) in a thin, even layer across the bottom three-quarters of the nori sheet.
Smear 1 tablespoon (15 ml / 0.5 fl oz) of the Chili Daikon in a horizontal line across the center of the rice.
Arrange ¼ of the apple matchsticks on top, followed by a sprinkle of ¼ of the sliced green onions.
Place your thumbs underneath the bamboo mat and use your fingers to hold the fillings in place.
Fold the bottom edge of the mat up and over the fillings, tucking the edge of the nori just over the apple to start the roll.
Lift the edge of the mat and continue to roll the nori forward, applying gentle, even pressure to create a tight cylinder.
Once rolled, gently shape it into a rectangle by pressing with your forefingers on top and your thumbs and middle fingers on the sides.
Set the finished roll seam-side down on a cutting board to rest.
Repeat the process with the remaining to make three more rolls.
Using a very sharp knife lightly dipped in water, slice each roll into 6 even pieces.
Serve immediately with Vegetarian Ponzu Sauce for dipping.
Don't overfill your roll! A modest amount of filling ensures the roll closes tightly and doesn't fall apart.
Keep a small bowl of water nearby (a tezu ) to dip your fingertips in. This prevents the sticky sushi rice from clinging to your hands as you spread it on the nori.
