Cut the nori sheets in half to have two rectangular sheets. Scissors work well for this.
Fold the rice wine vinegar into the brown rice.
Cut the peeled carrots into long pieces and then stack up the slices and cut into long thin stripes. Cut the asparagus through the center and then again to create thin pieces. Cut the mushrooms each in half and then thinly slice.
Lay the sheet of nori out horizontally.
Spread about a quarter cup of brown rice in a diamond shape at the right end of the nori sheet, exposing the two corners on that side.
Lay the veggie strips down across the brown rice at 2 and 7 o’clock. One end will go through the corner. The other end will be almost in the center of the nori sheet.
Pull the bottom right corner up to the top center as the veggies and rice are wrapped in and a cone is created.
Continue to roll the nori around to create a cone with a point at the bottom. Dip your finger in water and dollop it along the edge of the nori sheet. The water will help the remaining flap to seal up and keep the handroll intact.
Serve with coconut aminos or soy sauce and wasabi on the side to dip in your roll.