Soak the dry sushi rice in water for 45-60 minutes. Drain and cook in a pot with fresh water and a pinch of salt for 10-12 minutes until tender. Fluff and cool.

Bring a large pot of water to boil. Blanch Napa cabbage leaves for 2-3 minutes until softened, then plunge into ice water. Drain and set aside.

In a skillet, heat 1 tablespoon of oil over medium-high. Sauté onion, garlic, and ginger for 1-2 minutes. Add carrots, peppers, and mushrooms; stir for 3-4 minutes. Season with tamari, salt, pepper, onion powder, and red pepper flakes. Cook for another 1-2 minutes.

In a mixing bowl, combine cooked rice with sautéed vegetables and adjust seasoning. Take a cabbage leaf, place 1 ½ to 2 tablespoons filling at the base, fold sides over, and roll tightly.

In the skillet, heat another tablespoon of oil. Sear cabbage rolls seam-side down for 3-4 minutes per side until golden. In a small saucepan, sauté ginger and garlic in oil, then add tamari, rice vinegar, and maple syrup, stirring in water mixed with cornstarch to thicken.

Plate the cabbage rolls, drizzle with the sauce, and garnish with sesame seeds before serving hot.