Spicy Grilled Sweet Potatoes

4 medium sweet potatoes (about 3 pounds), scrubbed well
1 teaspoon kosher salt
1 teaspoon ground cumin
1 teaspoon paprika
1/2 teaspoon ground cinnamon
1/2 teaspoon chipotle powder
2 tablespoons apple cider vinegar
1/4 cup olive oil

Optional: Jalapenos and a bit of lime

Cover potatoes with cold salted water in a large pot, then bring to a boil. Simmer until slightly resistant when pierced with a sharp small knife, 5 to 7 minutes. Drain well. When cool, slice potatoes lengthwise.

Mix together salt, spices and apple cider vinegar; add oil in a slow stream. Brush this mixture on sweet potatoes.

Grill potatoes on a lightly oiled grill rack over medium heat, until grill marks appear and potatoes are cooked through, about 15 minutes. Serve potatoes warm.