Place the peanut butter, garlic, ginger, soy sauce, brown sugar, sesame oil, chili oil, and black vinegar into the bowl of a mini-food processor. Process until the mixture is well combined and forms a paste, 1 to 2 minutes. With the processor running, gradually add the chicken broth and process until the sauce is creamy and well combined, 1 to 2 minutes. Transfer to a large mixing bowl, cover, and set aside.