• 1 1/2 cups buttermilk or plain whole-milk yogurt
• 1 cup mayonnaise
• 1 to 2 tablespoons cider vinegar
• 1 tablespoon dehydrated onion flakes
• 1/2 teaspoon salt
• 1/2 teaspoon freshly ground black pepper

In a medium bowl, whisk together all ingredients until smooth. Cover and refrigerate at least 30 minutes before serving, or up to 1 week. Stir before using.