In a bowl stir together peanut butter, vinegar, soy sauce, coconut milk, garlic, sesame oil, and crushed red pepper. Stir in green onion.
To use, brush meat or poultry with sauce during the last 5 minutes of grilling. Heat remaining sauce until bubbly, stirring occasionally, and pass warmed sauce with meat or poultry. If desired, garnish sauce with a few chopped peanuts. Makes about 1 cup.