Cook 2 minced garlic cloves in a saucepan with olive oil, 1 minute.
Stir in ½ cup hoisin sauce, 2 tablespoons each rice vinegar and dry sherry, 1 tablespoon each soy sauce and ketchup and ⅓ cup water.
Simmer until thick, stirring, 20 minutes.
Let cool, then add ½ teaspoon sesame oil and 1 chopped scallion.
