Whole grain mustard and olive oil take the place of traditional mayonnaise in this lightened version of potato salad. It’s an ideal complement to roast chicken for serving at any early fall picnic or casual Sunday supper.
- 2 lbs red-skinned potatoes, cut into 1" pieces
- 1/4 cup apple cider vinegar
- 1 1/2 tablespoons whole grain Dijon mustard
- 1/4 cup plus 1 tablespoon olive oil
- Freshly ground black pepper
- 1 Fresno chile or red jalapeño, with seeds, thinly sliced into rounds
- 2 summer squash (such as zucchini or yellow crookneck squash; about 1 lb.), cut into 1" pieces
- 1 cup scallion, thinly sliced
- 1/2 torn fresh basil leaves
Place potatoes in a large pot; add cold water to cover by 2". Season with salt and bring to a boil. Cook until potatoes are just tender when pierced with a sharp knife but not mushy, 12–15 minutes. Drain; set aside.
Meanwhile, whisk egg yolk, vinegar, and Dijon mustard in a small bowl. Whisking constantly, slowly add ¼ cup oil, drop by drop, until well emulsified. Season to taste with salt and pepper; set aside.
In a large skillet, heat remaining 1 Tbsp. oil over medium-high heat. Add shallot and chile and cook, stirring occasionally, until shallot is soft and fragrant, 3–4 minutes. Add squash and cook, stirring occasionally, until tender but not mushy, 5–6 minutes.
Combine potatoes, squash mixture, scallions, and basil in a large bowl. Drizzle with some Dijon dressing and toss to coat. Season with salt and pepper. Serve chilled or at room temperature.