Aloo Chaat

Name: Aloo Chaat
Ingredients: 1 pound new potatoes or small Yukon Gold potatoes, scrubbed; Kosher salt; ½ small onion, chopped; 1 serrano chile, seeds removed if desired, chopped; 1 1-inch piece ginger, peeled, chopped; ½ cup chopped fresh cilantro, plus more for serving; ¼ cup vegetable oil; 1 15.5-ounce can chickpeas, rinsed, patted dry; Freshly ground black pepper; 2 teaspoons chaat masala; 2 tablespoons prepared tamarind chutney, divided; pinch of sugar; ¾ cup plain whole-milk Greek yogurt; 2 tablespoons melted ghee or clarified butter; ¼ cup sev (optional)