3 pounds baby Yukon Gold potatoes or fingerling potatoes, scrubbed but not
1 cup extra-virgin olive oil
1/4 cup Champagne vinegar
Kosher salt and freshly ground black pepper
2 celery hearts, thinly sliced (about 4 cups)
2 bunches radishes, thinly sliced
8 small scallions, white and light green parts only, thinly sliced (1 cup)
Bring a large pot of salted water to a boil. Add the potatoes and cook until tender, about 20 minutes. Drain and let cool slightly. Slice the potatoes 1/2 inch thick.
Meanwhile, in a large bowl, whisk the olive oil with the vinegar and season with salt and pepper. Gently fold in the potatoes and celery. Let stand at room temperature until cool, about 30 minutes. Just before serving, fold in the radishes and scallions and season with salt and pepper.
The potato salad without the radishes and scallions can be refrigerated overnight. Bring to room temperature before adding the radishes and scallions.