Start by preparing your vegetables: julienne carrots, finely shred cabbage, and dice or thinly slice bell peppers. Place them in a large mixing bowl.
In a separate small bowl, whisk together cornstarch, water, salt, minced garlic, and ginger until you get a thick, sticky batter.
Pour the batter over the chopped vegetables and toss gently until all pieces are evenly coated. The mixture should hold onto the veggies without dripping.
Heat oil in a deep frying pan or deep fryer over medium heat until it reaches about 350°F (175°C). You can test it by dropping a small batter piece—if it sizzles and rises to the surface, it's ready.
Using a spoon or your hands, carefully drop spoonfuls of the battered vegetable mixture into the hot oil. Fry in batches to avoid overcrowding, and cook until golden brown and crispy, about 4-5 minutes.
Use a slotted spoon to remove the fried balls and place them on a plate lined with paper towels to drain excess oil. Repeat until all the mixture is used.
In a large pan or wok, heat a tablespoon of vegetable oil over medium heat. Add minced garlic and ginger, and sauté until fragrant, about 30 seconds.
Pour in soy sauce and chili sauce, stirring to combine and heat until bubbling and slightly thickened, about 2 minutes.
Add the crispy vegetable balls to the sauce and toss gently to coat them thoroughly. Continue cooking for another 2-3 minutes until the sauce is glossy and sticky, and the balls are heated through.
Transfer the vegetable Manchurian to a serving dish, garnished with chopped green onions if desired. Serve hot, with a side of steamed rice or noodles.
