Preheat oven to 375° F. Line a baking sheet with parchment.

Stir tamari or coconut aminos and date syrup together in a small bowl.

Peel sweet potato and cut, lengthwise, into strips (just under 1/2 inch thick). Cut the sweet potato as if you were making sweet potato fries. Rub the sweet potato stripes with the mixture and sprinkle the flax seeds on top. Arrange on baking sheet. Bake about 25 minutes, until tender and light brown, gently turning halfway through.

Meanwhile, place the brown rice into a fine mesh strainer and rinse under cold, running water for 1-2 minutes.

Place brown rice into a small saucepan with water and vinegar (if you use rice vinegar). Place over high heat. Stir a few times and bring to a simmer. Lower heat, cover and allow to continue simmering for about 20 minutes, until all liquid is absorbed. Allow to sit for 10 minutes before uncovering.

Place a lined paper baking sheet onto your work surface and wet your fingers under some running water. Place one of your sheets on the baking sheet. Using wet hands, cover nori with a thin layer of brown rice. Arrange a third of your sweet potato strips in a single line along the width of the nori sheet, about one inch away from you. Arrange a few cucumber pieces right alongside the sweet potato strips.

Take the baking sheet and end of the nori sheet closest to you and tightly roll it over your fillings. Tuck the end of the nori in and continue rolling, using the baking sheet to press your roll tight, be careful not to tear the baking sheet. Once completely rolled, slice into about eight pieces with a really sharp knife.

Repeat using your remaining nori sheets and fillings.

Sprinkle with sesame seeds and serve with tamari/ coconut aminos. Use optional fillings such as scallions and serve with pickled ginger or wasabi if you wish.