Instructions

• Prepare the grill for direct cooking over medium-low heat (300° to 350°F) and preheat a perforated grill pan for about 10 minutes.
  Prepare the grill for direct cooking over medium-low heat (350°F) and preheat a perforated grill pan for about 10 minutes.
• Cut each sweet potato lengthwise in half, and then cut each half into ¾-inch slices. In a bowl whisk the oil, salt, and pepper and add the potato slices. Toss to combine.
• Spread the potatoes in a single layer on the grill pan and grill over direct medium-low heat, with the lid closed, until quite tender when pierced with the tip of a knife, 20 to 25 minutes, turning once or twice. Remove from the grill and cool to room temperature.
  Spread the potatoes in a single layer on the grill pan and grill over medium-low heat, with the lid closed, until quite tender when pierced with the tip of a knife, 20 to 25 minutes, turning once or twice. Remove from the grill and cool to room temperature.
• Meanwhile, in a large bowl whisk the yogurt, mayonnaise, vinegar, and mustard. Cover and refrigerate until needed.
• Add the cooled potatoes and chives to the bowl with the yogurt mixture. Gently stir to combine. Cover and refrigerate for at least 2 hours. Serve chilled.