Posting so I don't lose the recipe, no idea where I got it. I've made it many times and it's the best Chinese Chicken in a town where there are no Chinese restaurants! Some quantities are iffy, the original recipe didn't specify.
Heat 2 tbs. oil in wok or skillet over high heat. Add onions and cook until tender. Add garlic and ginger and cook until onions are golden brown. Add chicken and celery and cook until chicken is cooked through, about 5 minutes. Transfer to platter.
Add remaining oil. Add flour and stir until turning brown. Mix in broth, soy,and mustard. Boil until thickened. Add in chicken and broccoli, turning to coat. Mix in cashews and cook until heated through.