Cook the sushi rice according to package instructions. 

When done cooking, stir in the rice vinegar, salt, and sugar if using. 

Preheat the oven to 400 degrees Fahrenheit. 

Wash and peel the sweet potato and chop into roughly 2 inch long slices (about 1/2 inch thick).

Whisk the egg in a medium bowl. 

In another bowl, whisk together the rice flour, salt, and garlic powder.

In another bowl, add the breadcrumbs. 

Create an assembly line with the eggs, flour, breadcrumbs and a baking tray lined with parchment paper. 

Dip one sweet potato slice in the egg, then the flour, and then in the breadcrumbs. You can repeat this process a couple of times if you want the coating to be thicker. Place on the baking tray and repeat with all of the sweet potato wedges. Try to leave a bit of space between each sweet potato so they can really crisp up. 

To assemble the sushi, add a nori sheet to a sushi rolling mat. Add a layer of rice to the bottom 2/3 of the nori, leaving about 2 inches of space at the top (see image). Press the rice down firmly to ensure it sticks. It helps if your fingers are a bit wet. 

Add all your fillings to the bottom half of the rice. For this recipe we are using sweet potato, cucumber, and avocado. 

To roll, use the bamboo mat to gently fold the roll up and out. Keep rolling until you get to the last inch of the nori. Use some water to seal the ends together. 

Repeat until all rice has been used. 

To make the dressing, whisk all ingredients together in a bowl. Add water until it is your desired consistency. Drizzle on top of the sliced sushi an enjoy!