Cold potato salad lands best when it tastes bright first and creamy second, and that’s exactly what this version does. The potatoes stay tender and substantial, the dressing clings instead of pooling at the bottom of the bowl, and the dill gives every bite a fresh, grassy lift that keeps the salad from feeling heavy. It’s the kind of side dish that gets scraped clean before the main course even hits the table.
The trick is balancing the potatoes and the dressing so neither one disappears. Red potatoes hold their shape better than starchy varieties, which matters here because you want distinct pieces, not a mash. Buttermilk brings tang and looseness, while mayonnaise and sour cream give the dressing enough body to coat the cubes without turning pasty. Dijon sharpens everything up, and the chives and red onion add just enough bite to keep the flavor moving.
Below, I’ll walk through the part that matters most: how to season the potatoes while they’re still warm so the salad tastes developed instead of flat. I’ve also included a few simple swaps and the storage note that helps this salad taste its best after chilling.
I made this for a cookout and the dressing coated every potato instead of sliding off. Chilling it for two hours made the dill and Dijon pop, and the red onion stayed crisp without taking over.
Save this dill potato salad with mustard buttermilk dressing for the days when you want a chilled side dish with real tang and fresh herb flavor.
Why the Potatoes Need to Cool Before the Dressing Goes On
Warm potatoes drink in seasoning better than cold ones, but piping hot potatoes will thin the dressing and make the salad look greasy. Let the cubes drain well, then cool them until they’re just warm to the touch before you add the dressing. That sweet spot lets the potatoes absorb salt and tang without collapsing.
Red potatoes are the right choice because they hold their shape after boiling. If you use a waxy potato and stop cooking the minute the fork goes in, the centers stay chalky. If you overcook them, the cubes split at the edges and start breaking apart as soon as you toss them.
What Each Ingredient Is Doing in the Bowl
- Red potatoes — Their waxy texture keeps the salad chunky and defined. Yukon golds work in a pinch, but avoid russets here because they turn soft and absorb too much dressing.
- Buttermilk — This gives the salad its light tang and loosens the dressing so it coats instead of smothering. If you don’t have it, use plain kefir or thin plain yogurt with a splash of water, but the flavor will be a little less clean.
- Mayonnaise and sour cream — Mayo gives the dressing stability, and sour cream adds a cool, creamy edge. Using only mayo makes the salad heavier; using only sour cream makes it a little too sharp and thin.
- Dijon mustard — Dijon sharpens the whole bowl and helps the dressing taste finished. Yellow mustard will work, but it brings a flatter, more familiar deli-salad flavor.
- Fresh dill and chives — These herbs are what keep the salad tasting fresh after chilling. Dried dill won’t give the same bright finish, so use fresh if you can.
- Red onion — A small amount adds crunch and bite without taking over. Dice it fine so the sharpness spreads through the salad instead of landing in harsh pockets.
How to Build the Dressing So It Stays Creamy After Chilling
Boiling the Potatoes to the Right Point
Cook the potatoes in salted water until a knife slides in with only a little resistance. They should be tender, but not falling apart at the edges. Drain them well and let the steam escape for a few minutes so the dressing doesn’t get watered down. If the potatoes sit in hot water too long, they’ll start to absorb too much moisture and turn mealy.
Whisking the Dressing Until It’s Smooth
Mix the buttermilk, mayonnaise, sour cream, Dijon, salt, and pepper until the dressing looks fully blended and slightly glossy. Don’t rush this part with cold ingredients straight from the fridge if you can help it, because very cold mayo and sour cream can cling in streaks and take longer to smooth out. The dressing should taste a touch stronger than you want the final salad to taste, since the potatoes will soften the intensity once they go in.
Combining Without Breaking the Potatoes
Add the potatoes, dill, chives, and red onion to a wide bowl, then pour the dressing over and fold gently with a spatula. Stir just enough to coat every piece. If you mix aggressively, the outer edges of the potatoes smear and the bowl starts looking heavy instead of fresh. Once combined, chill the salad for at least 2 hours so the flavors settle and the dressing thickens slightly.
Make It Lighter with Greek Yogurt
Swap the sour cream for plain Greek yogurt if you want a sharper, tangier salad with a little less richness. The texture turns a bit tighter and the flavor gets brighter, which works especially well if you’re serving this alongside grilled meats or anything smoky.
Dairy-Free Version That Still Tastes Balanced
Use a dairy-free mayo and unsweetened dairy-free yogurt in place of the buttermilk and sour cream. Add a small splash of lemon juice to replace some of the tang that buttermilk normally brings. The salad will be a little less plush, but it still gets that creamy, herb-forward finish.
Extra Herbs for a Brighter Finish
Add a little parsley or tarragon if you want the salad to taste even fresher and more layered. Parsley keeps the flavor clean, while tarragon adds a subtle anise note that plays nicely with the mustard. Keep the total herb amount moderate so the dill still leads.
Storage and Reheating
- Refrigerator: Store covered for up to 3 days. The dressing may thicken as it chills, and the herbs will soften a little, but the flavor stays strong.
- Freezer: Don’t freeze this salad. The potatoes turn grainy and the creamy dressing separates once thawed.
- Reheating: This salad is meant to be served cold. If it firms up too much in the fridge, let it sit at room temperature for 10 to 15 minutes and stir once before serving.
Answers to the Questions Worth Asking
Dill Potato Salad with Mustard Buttermilk Dressing
Ingredients
Equipment
Method
- Bring a pot of water to a boil in a Dutch oven, add the red potatoes, and simmer until tender, about 15–20 minutes. Look for cubes that pierce easily with a fork.
- Drain the cooked potatoes and let them cool to room temperature. The potatoes should be warmless before dressing to avoid thinning.
- In a bowl, whisk together buttermilk, mayonnaise, sour cream, Dijon mustard, salt, and pepper until smooth. The mixture should look creamy with no mustard streaks.
- Combine the cooled potatoes with fresh dill, fresh chives, and red onion in a large bowl. Toss until the herbs and onion are evenly distributed.
- Pour the mustard buttermilk dressing over the potato mixture and toss gently to coat. The potatoes should glisten but still hold their shape.
- Cover and refrigerate the potato salad for 2 hours before serving. Chill until thoroughly cold and the flavors taste melded.
