Heat 2 tbsp sesame oil on medium flame. Sauté 1 tsp garlic for a few seconds, then add 1 tsp ginger and 1 cup onion. Cook for 1–2 minutes until soft.
Add ½ cup carrots and 1½ cups mushrooms. Sauté until the mushroom moisture evaporates and the carrots soften slightly.
Add 1 cup capsicum, 1½ cups cabbage, 1 tsp vinegar, 1 tsp soy sauce, ½ tsp black pepper, 1 tsp salt, and 1 tsp chili flakes. Stir-fry on high flame for 2–3 minutes to keep them crunchy. Toss in 2 tbsp spring onion greens, cook for 1 minute, then turn off heat.
Transfer the veggie mixture to a plate and let it cool completely so it doesn't tear the rice paper.
Dip a rice paper sheet in normal water for 4–5 seconds. Place it on a flat surface, add 1–2 spoons of cooled filling in the center, fold the sides inward, and roll tightly.
Heat a little oil in a non-stick pan. Fry the dumplings for 2–3 minutes on each side until golden and ultra-crispy. Serve hot with Schezwan sauce or momo chutney!