Remove all fat from the chicken. Cut into ½-in. (1-cm) dice.
Cut the peppers in half and remove the core and seeds. Cut into strips ¼ in. (0.5 cm) wide.
Cut off the roots and withered parts of the green tops of the scallions. Split the scallions in half lengthwise and cut into 1-in. (2.5-cm) pieces. Combine with the peppers.