3 pounds new potatoes, washed (if potatoes are larger, cut into 1-1½ inch pieces)
6 scallions, chopped
6 tablespoons olive oil
6 tablespoons lime juice
1 cup sour cream
1 teaspoon kosher salt
½ cup loosely packed cilantro, chopped
Lime wedges for serving
1. Tear 4 sheets of foil, roughly 18 inches long. Divide the potatoes and scallions evenly among the 4 sheets and lift the foil around the potatoes and scallions to create a packet. Add 1 ½ tablespoons each of olive oil and lime juice to each packet. Tightly fold the edges to seal.
2. Prepare your grill with medium-high heat and let it get warm for at least 5 minutes. Add the packets and cover the grill. Let cook for 20 to 30 minutes, rotating the packets after the first 10 minutes. They’re ready when you can easily pierce the potatoes through the foil with a fork. Pull off the heat.
3. When the packets are cool enough to handle, open them and dump the potatoes and charred scallions into a large serving bowl. Use a potato masher or the back of a fork to coarsely mash most of the potatoes, leaving some intact. Add the sour cream and salt, stirring to coat, then fold in the cilantro. Serve warm or at room temperature with extra lime.