In a blender (or using an immersion blender), combine peanut butter, soy sauce, rice vinegar, brown sugar, chili oil, lime juice, garlic and warm water and blend until a loosened sauce. Add water (1 tablespoon at a time) if the mixture is still too thick.
3 Tbsp creamy peanut butter, 1.5 Tbsp soy sauce, 2 tsp rice vinegar, 1 Tbsp brown sugar, 1-2 tsp chili oil, 1 Tbsp lime juice, 1 clove garlic, ⅓ cup warm water