Mix Brown Sugar, Black Pepper, Dark Soy Sauce, Oyster Sauce and Rice Vinegar together. Mix till the Sugar dissolves.
Add 1 Tablespoon of the prepared Sauce to Boneless Chicken Cubes. Add Cornstarch, Salt and Baking Soda. Mix Well and rest for 15-20 Mins.
To the prepared Sauce, Add Oyster Sauce and Cornstarch for the Gravy, Mix till smooth.
Fry the Chicken Cubes in Oil till Golden Brown on both Sides on Low Heat. This will take only few minutes as its boneless. Keep them aside.
In the same pan, add Vegetable Oil. Saute minced Ginger Garlic then add thinly sliced red chilies.
Add the cubed Bell Peppers and Onions. Add salt to taste.
Add the prepared Sauce and Chicken Stock. I mixed 1 Bullion cube with half cup hot water as i didn't have any fresh Chicken Stock.
Add the Fried Chicken cubes once the sauce thickens a bit.
Garnish with freshly grounded pepper, red chilies and sesame oil.
Adjust water in the gravy according to your preference. Best served with white rice or fried rice.