In a mixing bowl, whisk together the soy sauce, chicken stock, rice vinegar, hoisin sauce, sesame oil, garlic powder, ginger, black pepper, ketchup, and minced garlic until smooth.
Add the pork, broccoli, carrots, and peppers to the slow cooker, then pour the sauce over top. Give everything a good stir so it’s evenly coated.
Cover and cook on low for 4 hours or high for 3 hours, until the pork is tender.
About 10 minutes before serving, thicken the sauce. In a small bowl, whisk together the cornstarch and water to make a slurry, then stir it into the slow cooker. Let it cook until the sauce thickens, about 10 minutes.
Stir in the cooked lo mein noodles until they’re well coated in the sauce.
Garnish with sesame seeds and green onions, then dig in!