In a large bowl, stir together the ginger, garlic, red pepper flakes, soy sauce, broth, and peanut butter. Stir in pork to coat. Set aside.
Heat oil in a wok or large skillet over medium-high heat. Stir in onions, and cook about 1 minute. Stir in cashews. Cook until unions are soft and translucent. Pour in pork and marinade. Cook until pork pieces are done, about 10 minutes. Stir in mixed vegetables, and cook 5 minutes more.