-
1
Rinse and drain brown rice and bring to a boil in a saucepan with water and a pinch of sea salt. Reduce heat to low, cover pan, and simmer rice for 30 minutes. Rice will not be dry.
-
2
Meanwhile, stir rice vinegar, cider vinegar, mirin, sugar, and 1/2 teaspoon sea salt in a bowl until sugar and salt have dissolved. Set the vinegar mixture aside.
-
3
Stir quinoa into rice and cooking liquid, bring to a boil, and reduce heat to low again; simmer until rice and quinoa are both tender and liquid is absorbed, about 15 more minutes. Transfer rice and quinoa into a large bowl and gently mix the vinegar mixture into the rice, spreading the grains out a little as you mix to help dry and cool the rice and quinoa. Let rice mixture cool until warm, about 10 minutes of stirring and fanning.
-
4
Place a nori sheet onto a sushi mat. With wet fingers, lightly press about 1/4 the rice mixture onto the nori sheet in an even layer, leaving about 1/2-inch uncovered at the top of the sheet. Place about 1/4 the shredded carrot, cucumber strips, and avocado slices in a line across the bottom of the rice.
-
5
Pick up the edge of the bamboo rolling sheet, fold the bottom edge of the sheet up, enclosing the filling, and tightly roll the sushi into a thick cylinder. Once the sushi is rolled, wrap it in the mat and gently squeeze to compact it tightly. Unwrap the roll and cut into 6 pieces to serve; repeat with remaining ingredients to make 4 rolls.
