Take the whiter part of the lemongrass and slice it diagonally into small pieces. Cut the green and red peppers into chunks
Bring the sauce to a boil in a small saucepan
Add some of the lemongrass and cook over low heat for a few minutes to allow the flavors of the sauce to come out and blend in
Heat a wok over medium-high heat without pouring in any oil
Saute the marinated thighs for a few minutes in a pan with the skin part of the thighs down
Fry for a few minutes with the skin browned, then turn the thighs and sauté for a further 3-4 minutes, until both sides are nicely browned. Brown on both sides
Take it out and cut it into bite-sized pieces with a knife
Slice the lemongrass directly into the pan, and roast it over a slow fire to bring out the flavor
Add the green and red bell peppers, pour in a little bit of oil, and sauté
Add the chicken pieces, pour in the sauce, and stir-fry it quickly or peddle it to the pan.