This creamy, tangy, lightly sweet buttermilk dressing is so easy to make with a handful of everyday ingredients. This dressing thickens as you chill it, so make it a few hours ahead of time for the best texture. Makes about 1 3/4 cups of the best lemon poppy seed dressing that keeps up to 10 days in the refrigerator.
Zest the lemon with a microplane grater and set aside.
Squeeze two tablespoons of lemon juice (depending on how juicy your lemons are, it could be 1/2 to 1 whole lemon.
In a medium bowl, combine the grated onion, sugar, poppyseeds, dry mustard, white wine vinegar, lemon zest, lemon juice, mayonnaise, buttermilk, salt and pepper.
Whisk to combine. Cover and refrigerate for several hours to thicken.