Heat oil in a skillet over medium heat; cook and stir pork until lightly browned, 5 to 7 minutes. Add onion and mushrooms and cook until slightly tender, 2 to 3 minutes. Add chicken broth, celery, salt, and black pepper; bring to a boil. Cover skillet, reduce heat to medium-low, and simmer until pork is tender, 15 to 20 minutes.

Mix bean sprouts and almonds into pork mixture. Whisk soy sauce and cornstarch together in a bowl until smooth; stir into pork mixture until thickened, 2 to 3 minutes.