In a bowl, combine sliced chicken, onion, carrot, gochujang, soy sauce, brown sugar, sesame oil, and any optional ingredients. Mix thoroughly. Cover and marinate in the fridge overnight or for at least 2 hours.

Heat a pan over medium-high heat. Add the marinated chicken and spread it evenly. Cook for about 5 minutes, stirring occasionally after the 1st minute.

Reduce heat to low, and cook covered for another 5 minutes until the chicken is cooked through.

Uncover, stir occasionally and cook until the sauce thickens. For a deeper caramelised flavour, stir less frequently to let the chicken slightly char.

Sprinkle some roasted white sesame and serve with rice, or lettuce leaves for wrapping.