Cold potatoes soaked in a tangy mustard buttermilk dressing hit that sweet spot between creamy and light. The red potatoes hold their shape, the dill keeps everything tasting fresh, and the Dijon gives the dressing enough backbone to cut through the richness without turning the salad heavy. It’s the kind of side dish that disappears fast because it tastes clean, bright, and familiar in the best way.
What makes this version work is the balance. Buttermilk brings acidity and a little looseness to the dressing, while mayonnaise and sour cream give it body so it clings to every piece of potato instead of pooling in the bottom of the bowl. I like to use red potatoes because they stay firm after boiling and chill up nicely, which matters here more than in a mash-heavy potato salad.
Below, I’ve included the small details that keep the potatoes from getting bland or gluey, plus a few useful swaps if you need to adjust the dairy or want to lean the salad a little more herb-forward.
The dressing coated every potato instead of sliding off, and after chilling the dill flavor came through even more. I made it the night before and it was even better the next day.
Save this dill potato salad with mustard buttermilk dressing for a chilled side that stays creamy, tangy, and fresh with every bite.
The Trick to Keeping Potato Salad Creamy Instead of Heavy
Potato salad goes wrong when the dressing is too thick, the potatoes are too hot, or both. Hot potatoes absorb seasoning fast, but they also can turn the mayo base oily if you dump everything together before the potatoes have had a chance to release steam. This recipe works because the potatoes cool just enough to hold their shape, then chill in a dressing that has enough acid to keep the flavor bright.
Red potatoes are the right call here because they’re waxy and firm. Starchy potatoes break down too easily and make the whole bowl dense. The other detail that matters is the mix of buttermilk, sour cream, and mayonnaise: buttermilk adds tang and loosens the dressing, sour cream adds a little body, and mayo smooths everything out so it coats instead of clumps.
What Each Ingredient Is Doing in This Bowl
- Red potatoes — These hold their shape after boiling and stay pleasantly firm after chilling. If you swap in russets, the salad gets softer and more prone to breaking apart.
- Buttermilk — This is what gives the dressing its clean tang and lightens the texture. If you don’t have it, mix milk with a little lemon juice or vinegar, but expect a slightly thinner result.
- Mayonnaise and sour cream — Together they make the dressing creamy enough to cling to the potatoes. Mayo brings richness, while sour cream adds a cooler, sharper note that keeps the salad from tasting flat.
- Dijon mustard — Dijon doesn’t just add mustard flavor; it sharpens the whole dish and helps the dressing taste intentional instead of bland. Yellow mustard works in a pinch, but it’s less smooth and a little more one-note.
- Fresh dill and chives — These herbs carry the freshness here. Dried dill won’t give the same clean green flavor, so use fresh if at all possible.
- Red onion — A small amount gives crunch and bite without taking over. Dice it finely so it blends into the salad instead of reading as a sharp onion chunk.
How to Build the Dressing So It Stays Smooth
Boiling the Potatoes Just Until Tender
Start the potatoes in cold water so they cook evenly from the inside out. Once the water comes to a boil, keep an eye on them and pull them as soon as a knife slides in with little resistance. If you overcook them, the cubes will split and the salad turns mushy before the dressing even goes on.
Mixing the Dressing Before the Potatoes Go In
Stir the buttermilk, mayonnaise, sour cream, Dijon, salt, and pepper together until the mixture looks smooth and loose. The dressing should pour easily and coat a spoon, not sit in a thick paste. If it tastes a little more tangy than you expect, that’s right — the potatoes will mute it once everything chills.
Combining and Chilling for Flavor
Fold the potatoes with the dill, chives, and onion first, then pour the dressing over and toss gently. Use a light hand so you don’t smash the cubes; a spoon or silicone spatula works better than a whisk here. The two-hour chill isn’t just waiting time. It’s when the potatoes absorb the seasoning and the onion softens enough to blend into the salad.
Make It Herbier
Add extra dill and a little parsley if you want the salad to taste greener and fresher. The texture stays the same, but the herb flavor gets louder and the mustard takes a back seat.
Dairy-Free Version
Use a plain dairy-free yogurt in place of the sour cream and a thick vegan mayo instead of the regular mayonnaise. You’ll still get a creamy dressing, though the tang will be a little different and less cultured than the original.
Lighter, Less Creamy Salad
Reduce the mayonnaise and add a little more buttermilk for a looser dressing with a sharper bite. The salad will taste brighter and less rich, but it won’t cling quite as thickly to each potato.
Storage and Reheating
- Refrigerator: Store covered for up to 3 days. The dressing will thicken a bit as it chills, so stir before serving.
- Freezer: Don’t freeze this salad. The potatoes turn grainy and the dairy dressing separates when thawed.
- Reheating: This salad is best served cold. If it has been in the fridge a while, let it sit at room temperature for 15 to 20 minutes so the dressing loosens and the flavors wake up.
Answers to the Questions Worth Asking
Dill Potato Salad with Mustard Buttermilk Dressing
Ingredients
Equipment
Method
- Bring a large pot of water to a boil over high heat. Add the red potatoes and boil until tender, 10-15 minutes, visible as the cubes easily pierce with a fork.
- Drain the potatoes and spread them on a sheet pan to cool. Let stand until no longer steaming, about 5-10 minutes, so the dressing won’t thin out.
- In a bowl, whisk together buttermilk, mayonnaise, sour cream, Dijon mustard, salt, and pepper until smooth. Stop when the mixture looks uniform and lightly thickened, with no streaks of mustard.
- Combine the cooled potatoes with fresh dill, chives, and red onion. Toss just until the herbs and onion are evenly distributed, with flecks of green throughout.
- Pour the dressing over the potato mixture and toss gently. Keep tossing until every potato cube is coated and the salad looks glossy rather than dry.
- Refrigerate the potato salad for 2 hours before serving. Cover and chill until cold and set, about the time the flavors meld.
