Preheat the oven to 425º.
Prepare the sushi rice by combining the rice vinegar, sugar and salt into a small saucepan. Heat until the sugar and salt have dissolved. Combine with the cooked rice and allow the rice to cool slightly.
Toss the sweet potato fries in the safflower oil and season with salt and fresh ground pepper. I recommend a few generous twists from each mill. Lay the sweet potato fries out on a baking sheet and roast them on the middle rack for 20-25 minutes, pausing to flip the fries halfway through.
While the sweet potato fries are roasting, prepare the teriyaki sauce by combining the garlic, ginger, tamari, water, maple syrup and rice vinegar in a small saucepan. Bring to a simmer.
In a separate bowl, combine the cornstarch with 2 tablespoons of water and stir until the cornstarch has dissolved into the water. Then add the cornstarch slurry to the saucepan. Simmer for about 10 minutes, stirring frequently. The sauce will begin to thicken. Allow the sauce to cool slightly (it will continue to thicken), then store in an airtight mason jar.
Remove the sweet potatoes from the oven and allow them to cool. When they are cool enough to handle, combine the panko breadcrumbs and ½ tsp of salt. Spread the breadcrumbs out on a shallow plate. Roll the roasted sweet potatoes in the panko breadcrumbs, gently pressing the breadcrumbs into the sweet potatoes.
Arrange the sweet potato fries back on to the baking sheet and spray them lightly with safflower oil. Then return the fries to the middle rack of the oven and roast for 10 minutes until the panko has crisped. See Recipe Notes.
Steam the asparagus and cut the spears into 3-inch pieces. See Recipe Notes.
Make the sushi rolls by laying 1 sheet of nori on the bamboo rolling mats. Wet your hands (this keeps the rice from sticking to your hands) and add 1/4 of the rice to the nori. Using the rice spreader or your hands, spread the rice out on sheet of nori, creating a thin layer of rice. Place a row of sweet potato fries, asparagus spears and mint leaves about 1/3rd of the way from the bottom of the nori sheet. Drizzle the fillings with teriyaki sauce.
Starting at the bottom of the mat, roll the mat up and over the filling. Gently press and then continue to roll. Unroll the mat and then use a sharp, wet knife to slice the roll into 6-8 pieces. See my blog post for visual instructions.
Top with sesame seeds and microgreens, if desired, and serve with tamari and wasabi paste.