Warm a wok over medium-high heat. Add the oil, ginger, mirin, tamari or aminos and cashews. Stir-fry 2 minutes to flavor the cashews with the ginger.
Add and stir-fry the red bell pepper and bok choy for 3 minutes, or until the red pepper turns bright red and bok choy wilts slightly.
Taste and add more tamari for a saltier flavor, if desired.