Preparation

• Slice the tenderloin crosswise into 1/2-inch-thick medallions. Cut the medallions into 1/2-inch-thick strips.
• In a medium bowl, whisk the soy sauce, mirin, brown sugar, cornstarch, and 1/4 tsp. white pepper until the cornstarch and sugar are dissolved. Add the pork, toss to coat, and marinate for 5 to 10 minutes.
• Heat 2 tsp. of the canola oil in a 14-inch wok or a 12-inch skillet over high heat until shimmering hot and swirl to coat the pan. Add the ginger and garlic and stir-fry until fragrant, about 10 seconds. Add the pork in a single layer and cook, undisturbed, for 1 minute. Turn the heat down to medium high and stir-fry until the meat is nearly cooked through, 2 minutes. Transfer to a serving bowl.
• Heat the remaining 2 tsp. canola oil in the wok over medium-high heat. Add the bok choy stalks and stir-fry until crisp-tender, about 2 minutes. Add the pork, bok choy leaves, and cashews, and stir-fry until the leaves are wilted, about 1 minute. Remove from the heat, toss with the sesame oil, and serve.