Heat the sesame oil in a saucepan over medium heat, then add the garlic. Saute the garlic until soft, stirring often.
Add the coconut milk and bring the milk to a light simmer, stirring often.
Add the peanut butter, hoisin sauce, rice vinegar, and Sriracha sauce, stirring to combine. Bring the sauce to a simmer, then remove from the heat and allow it to cool.
Use immediately or for best flavor allow the hoisin peanut sauce to sit for one to two hours to allow the flavors to meld prior to serving.