In a small bowl, mix broth, soy sauce, vinegar and cornstarch together. Set aside.
Warm oil in a wok or large skillet over medium-high heat. Add ginger and white part of scallions. Cook, stirring constantly, until scallions are just softened, about 1 minute.
Add pork and cook, tossing with tongs, until firm and no longer pink, 5 minutes.
Stir in sauce and 1/4 cup peanuts. Cook, stirring constantly, until sauce is thickened and pork is heated through, 2 minutes. If sauce is too thick, add broth, 1 Tbsp. at a time, until it reaches desired consistency. Top with green part of scallions and 1 Tbsp. peanuts.