Hoisin sauce tastes much better when mixed with other ingredients. This is also good as a marinade for fish, chicken, or beef. Try it with our Rice-Paper-Wrapped Salad Rolls.
Combine 1/2 cup water, hoisin sauce, vinegar, and onions in a small saucepan; bring to a boil over medium-high heat. Reduce heat to low; simmer until onions have softened, 7 to 9 minutes. If sauce becomes too thick, add water. Let cool. Transfer to a serving dish; top with chile paste and peanuts.