In a medium bowl, whisk together all the ingredients for the sauce. Set aside.
Warm the vegetable oil in a large skillet set over medium-high heat. Add the ground pork and 2 tablespoons of the sauce. Cook the pork, breaking it up into smaller pieces with a wooden spoon, until it’s no longer pink, about 6-7 minutes. Transfer the cooked pork to a clean bowl and set aside.
To the skillet, add the sliced celery, scallions, and mushrooms. Cook, stirring occasionally, for 3-4 minutes. If your skillet is getting too dry at any point, you can add 1-2 teaspoons of vegetable oil, as necessary.
Return the cooked pork to the skillet with the vegetables. Stir the sauce, then pour it into the skillet, tossing to combine. Cook the sauce with the pork and vegetables until it’s thickened, glossy and everything is well coated about 1 minute. Remove the skillet from the heat.
Finish with peanuts and cilantro before serving.
Leftovers can be stored in an airtight container in your refrigerator for 2-3 days.