Combine all the ingredients listed in the marinade in a glass or stainless steel bowl. Mix, cover, and refrigerate for at least 30 minutes or as long as overnight.
Pour the 3 tablespoons of oil into a wok, karhai, or large frying pan and set over medium-high heat. When hot, add the onions. Stir-fry for a minute.
Add the chicken with all its marinade. Stir-fry another 3 minutes or until the chicken is just cooked through.
Add the mint and stir-fry a few seconds.