I made a half recipe which was more than enough - didn't add any of the extras, except for chives ...
From Smitten Kitchen
4 pounds potatoes (I like tiny Yukon golds, but you can use whatever boiling potatoes you like for salads)(I used a 2 lb bag of little red - they look nicer)
1 3/4 cups Greek yogurt (I used full-fat but I think other fat levels would work)
1/4 cup sour cream
2 tablespoons freshly squeezed lemon juice (from half a big lemon)
1 tablespoon white wine vinegar
1 tablespoon minced fresh dill
1 medium garlic clove, minced
2 teaspoons kosher salt (I use Diamond brand; use less if you use another, read why here
)(used 1 tsp regular table salt)
Freshly ground black pepper
1 hothouse or English cucumber (1 pound), unpeeled but quartered lengthwise, seeds removed
More ideas for additions: Crumbled feta, chopped green olives, chopped fresh mint leaves or a minced hot chile
In a medium pot, cover your potatoes with cold water and bring them to a boil over high heat. Once boiling, reduce heat to medium-high and let potatoes simmer until tender enough that they can be pierced easily with a skewer or slim knife. I find that small potatoes tend to be done in roughly 30 minutes from the time I put them on the stove cold, but it’s best to start checking 5 to 10 minutes sooner.
Drain potatoes and let them cool completely. (This is a great step to do ahead, as it seems to take potatoes forever to cool. If you’re really in a rush, spread them on a tray and pop them in the freezer for 10 minutes.)
Meanwhile, in the bottom of a large bowl, stir together yogurt, sour cream, lemon juice, vinegar, dill, garlic, salt and lots of freshly ground black pepper.
Grate the cucumber on a box grater (or in your food processor’s shredding blade, if you like to get things done in one hundredth of the time) and try to remove some of the excess by squeezing out handfuls, pressing it in a mesh sieve with a spoon or wringing it in a square of cheesecloth or a lint-free dishtowel. Add to yogurt mixture.
Once potatoes are cool, cut tiny ones into quarters or larger ones into generous chunks. Add to cucumbers and yogurt and stir to coat.
Add any extra ingredients desired. Adjust seasonings to taste. Either eat immediately or keep in the fridge for up to three days.