Cold potato salad lives or dies by the dressing, and this one stays bright, creamy, and light enough that the potatoes still taste like potatoes. The dill comes through cleanly, the mustard gives the whole bowl a little backbone, and the buttermilk keeps the dressing from turning heavy or flat. It’s the kind of side dish that gets eaten before the burgers are even off the grill.
What makes this version work is the balance. Red potatoes hold their shape after boiling, so you get tender pieces instead of a mashed, gluey bowl. The dressing uses mayonnaise and sour cream for body, but buttermilk loosens it just enough to coat every cube without turning the salad dense. A short chill gives the onions time to soften and the herbs time to bloom into the dressing.
Below I’ve added the small details that matter here: how to keep the potatoes from breaking apart, why the salad tastes better after a rest, and what to swap if you need a dairy-free version.
The dressing coated the potatoes without getting watery, and the dill tasted fresh even after chilling. I served it the next day and it was still creamy with just the right tang.
Save this dill potato salad for the kind of side dish that stays creamy, tangy, and full of fresh herbs after chilling.
The Trick Is Keeping the Potatoes Whole Enough to Hold the Dressing
Potato salad goes wrong when the potatoes are cooked past the point of tenderness. You want them soft enough that a fork slips in easily, but still firm enough that the cubes keep their edges after tossing. Red potatoes are the right choice here because they’re waxy and hold together better than russets, which tend to fall apart and make the salad starchy.
Drain the potatoes well and let them cool before you add the dressing. If they’re steaming hot, they’ll loosen the dairy and thin the sauce. If they’re completely cold, they won’t absorb much flavor. Warm is the sweet spot — just enough heat left that the mustard and herbs cling to the surface.
What Each Ingredient Is Actually Doing in the Bowl
- Red potatoes — These hold their shape after boiling and give you clean, tender bites. If you swap in Yukon Golds, the salad turns a little richer and softer; it still works, but you’ll need to handle them more gently when mixing.
- Buttermilk — This is what keeps the dressing light and tangy. There isn’t a perfect substitute for the flavor, but plain yogurt thinned with a splash of milk gets close if that’s what you have.
- Mayonnaise and sour cream — These build the creamy base and keep the dressing from tasting sharp or thin. Full-fat versions give the best body; low-fat versions can work, but the dressing will be looser and less silky.
- Dijon mustard — Dijon sharpens the dressing and keeps the dairy from tasting flat. Yellow mustard won’t give the same depth, though it can stand in if that’s all you’ve got.
- Fresh dill and chives — Fresh herbs matter here because the salad is served cold and the herbs need to carry the flavor. Dried dill won’t give the same clean finish, so use less of it and expect a more muted result if you must substitute.
- Red onion — A small amount adds bite and crunch without taking over. Dice it finely so it softens in the dressing; big chunks stay harsh and throw off the texture.
How to Build the Salad So It Stays Creamy After Chilling
Boiling the Potatoes
Start the potatoes in salted water and cook them until a knife slides in without resistance. Pull them before they start collapsing at the edges. If you overcook them, they’ll shed starch into the dressing and turn the whole bowl pasty. Drain them well, then spread them out for a few minutes so the surface moisture can evaporate.
Mixing the Dressing
Whisk the buttermilk, mayonnaise, sour cream, Dijon, salt, and pepper until the mixture looks smooth and loose enough to pour. The dressing should coat a spoon but still move easily. If it looks too thick, add a small splash more buttermilk. The goal is a creamy dressing that settles into the potatoes instead of sitting on top of them in clumps.
Combining and Chilling
Add the potatoes, dill, chives, and onion to a large bowl, then pour the dressing over and fold everything together gently. Stir with a light hand so the potatoes stay intact. Cover and chill for at least 2 hours. That rest is what lets the onion mellow and the mustard come forward without tasting sharp.
Swap in Greek yogurt for a tangier, lighter bowl
Replace the sour cream with full-fat Greek yogurt if you want extra tang and a slightly firmer dressing. The salad will taste brighter and a little less rich. Thin it with a touch more buttermilk if it starts to feel too thick after chilling.
Make it dairy-free without losing the creamy texture
Use a plant-based mayo and unsweetened dairy-free yogurt or sour-cream alternative, then add a splash of lemon juice for brightness if the substitute tastes flat. You won’t get the exact buttermilk flavor, but the salad still comes together with a creamy, tangy finish.
Add hard-boiled eggs for a more substantial side
Chopped hard-boiled eggs make this feel closer to a picnic-style potato salad and add extra richness. Fold them in at the very end so they don’t break down. The salad gets a little heavier, which works well if it’s serving as part of a larger summer spread.
Storage and Reheating
- Refrigerator: Store covered for up to 3 days. The dressing may thicken slightly as it chills, so give it a gentle stir before serving.
- Freezer: Don’t freeze this one. The dairy separates and the potatoes turn mealy after thawing.
- Reheating: This salad is meant to be served cold. If it has been in the fridge for a while, let it sit at room temperature for 15 to 20 minutes so the dressing loosens and the flavors wake back up.
Answers to the Questions Worth Asking
Dill Potato Salad with Mustard Buttermilk Dressing
Ingredients
Equipment
Method
- Bring a Dutch oven of water to a boil and cook the cubed red potatoes until tender, about 10–15 minutes, until a knife slides through easily. Drain thoroughly so the salad doesn’t get watery.
- Spread the drained potatoes on a sheet pan and cool until no longer hot, about 10 minutes, until they look dry and separate.
- In a bowl, whisk together buttermilk, mayonnaise, sour cream, Dijon mustard, salt, and pepper until smooth and slightly thick, about 1 minute. Pause to scrape the sides so there are no mustard streaks.
- Add the cooled potatoes to a bowl and toss with fresh dill, fresh chives, and red onion until evenly distributed with herbs. The onions should be visible throughout.
- Pour the dressing over the potato mixture and toss gently until the potatoes look lightly coated and creamy, not dry. If needed, add a pinch more salt to taste.
- Cover and refrigerate for 2 hours before serving so the flavors meld and the dressing sets slightly. Serve chilled and garnish with extra dill if desired.
