While the milk is standing, whisk together the sour cream and mayonnaise. Then add in the garlic, Cajun seasoning, dried dill, salt, and pepper.
1/2 cup sour cream, 1/4 cup mayonnaise, 2 cloves garlic, 1 tablespoon Cajun seasoning, 1 teaspoon dried dill, 1/4 teaspoon kosher salt, dash black pepper