Mix corn starch, soy sauce, vinegar, salt, pepper powder and water in a bowl. Make sure there are no lumps and set aside.
In a bowl boil 3-4 cups of water. Once it boils add green beans, broccoli and cauliflower and baby corn. Boil for 2-3 minutes.
Turn down the heat and transfer the vegetables to a fine mesh sieve. Set aside.
In a thick bottom pan or wok heat oil till it is smoking.
Add garlic and let it turn light brown.
Then add the peppers and sauté for a minute.
Add carrots, mushrooms and scallions followed by cabbage.
Add in the blanched vegetables and chestnuts and mix well.
Transfer the cornstarch mixture to the pan and mix well till it coats the vegetables.
Turn off the flame and serve topped with scallions.