Combine the chicken thigh fillets with the minced garlic, soy sauce, vinegar, and bay leaves in a bowl. Allow the mixture to marinate for at least 20 minutes or refrigerate overnight for deeper flavour.
Heat 1 tablespoon of oil in a frying pan over medium-high heat. Remove the chicken from the marinade & reserve the marinade for later. Sear the chicken in the pan for about 1 minute on each side until slightly browned but not fully cooked. Set the chicken aside on a plate.
In the same pan, add the remaining oil. Turn the heat down to medium and cook the onion for 4-5 minutes, to soften. Add the additional 3 cloves of garlic and cook for 1 minute, stirring.
Combine the boiled water with the stock cube and brown sugar. Stir to combine & to dissolve the sugar. Tip this into the pan along with the reserved marinade and pepper corns. Bring to a simmer over medium-high heat, reduce heat to medium and cook for about 5 minutes.
Return the seared chicken to the pan. Simmer uncovered for 15-20 minutes, turning the chicken once, halfway through the cooking time. The sauce should be like a thick syrup. If the sauce needs to longer to thicken, remove the chicken (to avoid it drying out) and allow the sauce simmer alone until it reaches this syrup likeness.
Coat the chicken well with the glaze and serve over rice.
Garnish with sliced Spring onions & steamed Asian greens.