1. Drain tofu well and squeeze between a few paper towels (or cheesecloth, or a tea towel) to remove excess water. Crumble into a large bowl. Combine vegetables with tofu. Pour in sesame oil and soy sauce, 1 tablespoon at a time, mixing with hands to coat ingredients.
2. Sprinkle in vegan sugar. Add ginger and garlic, then mix with hands to incorporate. Fill a small bowl with water (for sealing wrappers) and prepare an assembly line.
3. Scoop roughly 1 tablespoon of the tofu/vegetable mixture into the center of the wrapper. Wet fingertips with water and dampen the edges of the wrapper. Fold one side over to make a semicircle, then press along the edges to seal. Continue until all the mixture, or the wrappers, have been used.
4. Heat a large, nonstick skillet over medium heat. Pour 1 or 2 tablespoons light oil into the pan and arrange dumplings so they are not touching.
5. Gently brown on both sides, then carefully pour in 2 tablespoons water and cover the pan. Cook for 2 minutes, until heated through, then remove from heat. Combine soy sauce and vinegar for dipping sauce, and serve.
These are time consuming, but well worth it. These freeze very well; simply arrange the uncooked dumplings on a baking tray and freeze overnight, then transfer to freezer bags or containers. To cook from the freezer, pop them directly into the pan (unthawed). You may need to let them steam for a little longer to heat them through.
Source of recipe: I modified the recipe for mandu from www.maangchi.com [1] and added some of my own touches.