How to Make It
Whisk together stock, soy sauce, honey, vinegar, mustard, cornstarch, and crushed red pepper in a bowl. Set aside.
Heat a wok or large skillet over medium-high. Add pork; cook, stirring often and scraping bottom of pan with a wooden spoon to loosen browned bits, until pork is browned and crumbled, 4 to 5 minutes. Remove pork from pan with a slotted spoon.
Add bok choy and carrots to drippings in pan; cook over medium-high until slightly wilted, 2 to 3 minutes. Add stock mixture and pork. Bring to a boil; cook until thickened, 1 to 2 minutes. Remove from heat. Stir in sesame oil.
Serve over rice, and sprinkle with sesame seeds, if desired.