Use whichever bell peppers are available, if red bells are not.
In a large bowl, mix together the soy sauce and sherry. Add the chicken and stir to coat. Marinate for at least 15 minutes.
Heat a flat-bottomed wok or large skillet over high heat until almost smoking. Add the oil to the pan and swirl to coat the pan. Immediately add the scallions and a large pinch of salt. Cook, stirring constantly, until the scallions wilt and smell fragrant, about 30 seconds. Add the bell pepper and cook, stirring, until the bell pepper softens, about 2 minutes. Add the garlic and ginger and stir constantly for 10 seconds. Add the chicken and any leftover marinade and cook, stirring constantly, until the chicken is cooked through, about 1 minute. Turn off the heat and add the sesame oil. Stir then serve