SWEET-POTATO SALAD WITH MUSTARD VINAIGRETTE

Steps:

• Peel potatoes and halve lengthwise. Cut lengthwise into 3/4-inch-thick wedges, then cut wedges crosswise into 1-inch pieces.
• Steam potatoes in a steamer over boiling water in a large pot, covered, until just tender, 10 to 12 minutes or boil which ever you prefer.
• While potatoes steam, whisk together mustard, vinegar, and salt in a large bowl, then add oil in a slow stream, whisking until emulsified.
• Add hot potatoes to dressing and gently toss to combine well. Cool salad to room temperature, about 15 minutes.
• Add scallions and salt to taste and gently toss.
• Salad (without scallions) can be made 2 hours ahead. Toss in scallions just before serving.