Indian Potato Fritter Sandwich (Vada Pav)

A staple of Mumbai street stalls, these aromatic fried potato-fritter sandwiches are slathered with coriander and tamarind chutneys and served on a buttered, toasted roll.

Yield: serves 8-10

For the Chutneys

2 cups chopped cilantro
2 tbsp. fresh lemon juice
2 tbsp. roasted peanuts
2 tbsp. desiccated coconut
2 tsp. kosher salt
2 jalapeños, stemmed
8 oz. tamarind paste
1 tbsp. canola oil
2 tsp. fennel seeds
¹⁄₂ tsp. black mustard seeds
1 serrano chile, stemmed and finely chopped
³⁄₄ cup packed dark brown sugar
¹⁄₄ cup raisins
1 tsp. hot paprika

For the Vada and Serving

¹⁄₂ tsp. kosher salt, plus more to taste
1 ¹⁄₂ lb. russet potatoes, peeled and cut into 1" chunks
2 tbsp. canola oil, plus more for frying
³⁄₄ tsp. black mustard seeds
¹⁄₈ tsp. asafetida
1 (1/2") piece ginger, peeled and minced
2 cloves garlic, minced
³⁄₄ tsp. ground turmeric
1 small yellow onion, finely chopped
1 serrano chile, stemmed and finely chopped
¹⁄₄ cup finely chopped cilantro
¹⁄₄ cup finely chopped mint
2 tsp. fresh lemon juice
1 cup chickpea flour
¹⁄₄ cup rice flour
¹⁄₄ cup plain yogurt
1 tsp. ground coriander
¹⁄₂ tsp. ground cumin
¹⁄₂ tsp. baking soda
2 tbsp. unsalted butter
8 store-bought Parker House rolls, split but left hinged

Instructions

Make the coriander chutney: Place cilantro, lemon juice, peanuts, coconut, salt, jalapeños, and ½ cup water in a blender, and puree until smooth. Transfer to a small bowl and set aside.
Make the tamarind chutney: Heat the tamarind paste and 2 cups water in a 1-qt. sauce pan over medium-high heat; cook, stirring, until tamarind dissolves. Pour through a medium strainer into a small bowl, pressing on solids to extract all pulp; discard solids and set aside pulp. Heat oil in a 2-qt. saucepan over medium-high heat. Add fennel, mustard seeds, and chile; cook, stirring, until lightly browned, 2-4 minutes. Add reserved tamarind pulp, brown sugar, dates, raisins, paprika, and 1 cup water, and bring to a boil. Reduce heat to medium-low and cook, stirring, until reduced and thick, about 10 minutes. Transfer to a small bowl and set aside.
Make the vada: Bring a 4-qt. saucepan of salted water to a boil, and add potatoes; cook until tender, about 10-12 minutes. Drain in a colander, then pass through a potato ricer into a large bowl; set aside. Heat oil in a 2-qt. saucepan over medium-high heat. Add mustard seeds and asafetida and cook, stirring, until fragrant, 3-4 minutes. Add ginger and garlic and cook, stirring, until lightly browned, 20-30 seconds. Add ½ tsp. turmeric, onion, and chile, and cook, stirring, until lightly browned, 3-4 minutes. Transfer to bowl with potatoes, along with cilantro, mint, and juice; season with salt and stir until well combined. Shape mixture into 2" balls and transfer to a parchment paper-lined baking sheet; refrigerate for 1 hour. Meanwhile, whisk together ½ tsp. salt, remaining turmeric, chickpea and rice flours, yogurt, coriander, cumin, baking soda, and ¾ cup water until smooth; set aside.
To assemble, heat butter in a 12" skillet over medium-high heat. Add rolls, cut sides down, and cook until toasted, about 3 minutes. Spread 1 tbsp. coriander chutney inside top of each roll and 1 tbsp. tamarind chutney inside bottom of each roll. Place a potato ball in each and close, then gently smash.