1 tablespoon vegetable oil
1 small yellow onion, diced (about 1/2 cup)
3 medium cloves garlic, minced (about 1 tablespoon)
2/3 cup hoisin sauce
1/2 cup ketchup
1/3 cup dry sherry
1/3 cup rice vinegar
1/4 cup honey
2 tablespoon soy sauce
1 tablespoon Sriracha
1/2 teaspoon ground Szechuan peppercorns
1/2 teaspoon ground white pepper
1/4 teaspoon Chinese five-spice powder
Heat oil in medium saucepan over medium heat until shimmering. Add onion and cook until softened, about 5 minutes. Add garlic and cook until fragrant, about 30 seconds.
Add hoisin sauce, ketchup, sherry, vinegar, honey, soy sauce, Sriracha, Szechuan peppercorns, white pepper, and five-spice powder; stir to combine. Bring to a boil, then reduce heat to low and simmer until slightly thickened, about 15 to 20 minutes, stirring occasionally.
Blend sauce until smooth with a stick blender, or transfer to jar of a regular blender and blend. Let cool to room temperature, transfer to a jar and store in refrigerator for up to a month.