Dahi Puri With Black Chickpeas

Name: Dahi Puri With Black Chickpeas
Ingredients: ½ cup dried black chickpeas, soaked overnight, drained (Rancho Gordo desi chana, recommended); Kosher salt; 3 medium Yukon Gold potatoes (about 1 lb.), peeled, cut into 1 pieces; 1 tsp. ground turmeric; ½ cup tamarind concentrate (such as Swad); 2 Tbsp. date syrup; 2 tsp. finely chopped, peeled ginger; 4 Tbsp. chaat masala, divided, plus more for serving; 3 tsp. ground cumin, divided; 3 tsp. red chili powder, divided; 2 cups plain whole-milk yogurt; Vegetable oil (for frying; about 8 cups); 1 7-oz. packet pani puri; ½ cup Scallion Chutney; 1 small red onion, finely chopped; 1 cup coarsely chopped cilantro; 1 cup coarsely chopped mint; 1 8-oz. package thin sev; A deep-fry thermometer