Potatoes make satisfying side dishes in all seasons, summer included. What would a picnic be without potato salad? Opinions on which ingredients are essential to potato salad can vary (maybe your must-include is hard-cooked egg, or diced onion, or sweet pickle relish). Regardless, the starting point must be a basic recipe that promises a good outcome every time. My stripped-down method does just that -- all the salad needs are creative additions to make it your own.
Set a steamer basket in a Dutch oven (or large pot with a lid), and add enough salted water to come just below basket; bring to a boil. Place potatoes in basket, cover pot, and reduce heat to a gentle simmer. Steam potatoes, gently tossing occasionally, until tender, 15 to 25 minutes. Meanwhile, in a large bowl, combine vinegar, scallion whites, 1 teaspoon coarse salt, and teaspoon pepper. Add hot potatoes to vinegar mixture; toss to combine. Cool to room temperature, tossing occasionally, about 1 hour. Add mayonnaise and scallion greens to cooled potatoes; mix gently to combine. Serve, or cover and refrigerate up to 2 days.
For a potato salad that doesn't end up mushy, use waxy potatoes, which keep their shape better than starchy baking potatoes.For even cooking, make sure the potatoes are cut into uniform pieces.For a hint of sweetness, add a pinch of sugar to the vinegar mixture. For extra tang, sub in sour cream for some of the mayonnaise.For warm-weather picnics, make a no-mayo version: replace the mayo in my basic recipe with 1/2 cup olive oil whisked with 1 tablespoon Dijon mustard.For balanced flavor, keep your mix-ins simple (but still be creative). I like celery and hard-cooked egg. Take it easy on salty and acidic ingredients (combining, say, pickles, capers, and olives would be too much).Mix-and-Match Mix-Ins (add after salad cools)Sliced celeryDiced red onionSweet pickle relishChopped picklesSlivered green olivesCapersChopped herbsChopped hard-cooked eggsCrumbled bacon