Ingredients

1 1/2 pounds Yukon gold potatoes, scrubbed and cut into 3/4-inch cubes

2 tablespoons olive oil

1 tablespoon Dijon mustard

1 tablespoon white-wine vinegar

4 celery stalks, halved lengthwise and thinly sliced

2 scallions, thinly sliced

Coarse salt and ground pepper

Preparation

Set a steamer basket in a large saucepan. Fill with enough water to come just below basket. Bring to a boil; place potatoes in basket, and reduce to a simmer. Cover, and steam until tender, 15 to 20 minutes.

Meanwhile, in a large bowl, whisk together oil, mustard, and vinegar. Add celery, scallions, and hot potatoes, and season with salt and pepper; toss to combine. Cool to room temperature, tossing occasionally, about 1 hour.