Heat 1 teaspoon oil in a pan or wok on medium-high flame.
Add 2–3 cloves minced garlic, 1 inch grated ginger, and 2 finely chopped green chilies (if you like spicy). Sauté for 30 seconds until aromatic.
Add ½ cup chopped onions and stir-fry until they turn translucent.
Now add the vegetables: 1 cup shredded cabbage, ½ cup grated carrot, and ½ cup finely chopped capsicum. Stir well.
Cook the veggies on high heat for 2–3 minutes only. The idea is to keep them slightly crunchy, not mushy.
Add seasoning: 1 tablespoon soy sauce, 1 teaspoon vinegar, 1 teaspoon black pepper powder, and salt to taste. Mix quickly so veggies absorb the flavors.
Turn off the heat, add 2 tablespoons chopped spring onion greens, and give it a final mix.
Transfer the filling to a bowl and let it cool completely before stuffing into momos. (If you use hot filling, the dough will turn soggy and break).