Heat a wide pan at medium heat and add the oil. Once hot, add the onions. Saute for 3-4 minutes. Add the chopped ginger, garlic and mix well. After 2-3 minutes, add the diced bell peppers. Season with some salta and pepper. Cook for 5 minutes. Remove from pan and keep aside.
To the same pan, add the soy sauce, tomato ketchup, vinegar, red chilli sauce and sugar to the pan. Mix well. Add the water. Make a slurry of corn starch and add to the sauce. Cook until the sauce has thickened. Turn off heat and keep aside.
In a bowl, place all the dry ingredients and mix well. Start adding a little bit of water at a time and stirring the ingredients. Once the batter has reached a consistency where it can easily stick to the baby corn, keep aside.
Heat the frying oil in a deep pan like a kadai or a wok. Keep the oil at medium heat. Check if the oil is hot by gently dropping a piece of battered baby corn. The oil should start bubbling where the piece of baby corn was dropped and start gently browning in 3-4 minutes.
Now, you can start frying the other pieces of the baby corn. Make sure all the pieces are coated with the batter well and make sure the pan is not crowded while frying. Once all the pieces have turned golden brown, remove from the pan using a skimmer. Place on a paper towel lined plate or bowl.
Repeat until all the pieces have been fried. Now heat the pan with the sauce gently.Add some seasoning if required. Once hot, add back the onion- bell pepper mixture. Mix well and add the fried baby corn. Gently toss to coat everything with the sauce.
Top with white pepper and chopped green onions. Add some chopped cilantro as well if needed. Serve hot.