Fry the peanuts, pepper flakes pinch salt in 1 teaspoon peanut oil for about 1 minute. Set aside.
Slice the stems off of 1 bunch of bok choi, and cut them into ½ inch pieces. Leave the leaves whole, or if they are very large cut in half crosswise. Heat the other tablespoon oil until very hot then add the onion and ginger and stir-fry for about 1 minute. Add the bok choi stems and leaves and stir-fry until wilted and glossy. Then add the soy sauce and cornstarch mixture and cilantro and stir-fry for another minute. Add the peanut mixture and serve warm.