Instructions

1. Grate 2 Persian cucumbers on the large holes of a box grater into a small bowl. Sprinkle with 1 teaspoon of the kosher salt and toss to combine. Let sit for 5 to 10 minutes. Meanwhile, finely grate the zest of 2 medium lemons (2 to 3 tablespoons) into a large bowl for the pakora and set aside. Juice the lemons until you have 3 tablespoons.
2. Drain the cucumber into a colander. Using your hands, squeeze out the excess liquid from the salted cucumber and return to the bowl. Add the lemon juice and 1 cup plain Greek yogurt, and stir to combine. Taste and season with more kosher salt as needed. Transfer to a small serving bowl, cover, and refrigerate until ready to serve.
3. Add the remaining 1 1/2 teaspoons kosher salt, 1 cup besan (chickpea) flour, 1/4 cup rice flour, 2 teaspoons ground turmeric, 1 1/2 teaspoons cumin seeds, 1 1/2 teaspoons kalonji (nigella) seeds, 1 teaspoon Kashmiri chili powder, and 1/8 teaspoon asafetida powder to the bowl of lemon zest. Whisk to combine.
4. Trim and thinly slice 1 to 2 serrano chiles. Cut the dark green parts from 1 large leek and discard; halve and rinse the white and light green parts, then thinly slice crosswise (about 1 1/2 cups). Coarsely chop the leaves and tender stems from 1/3 medium bunch fresh cilantro until you have 1/2 cup.
5. Add 2/3 cup water to the flour mixture and whisk until smooth. The batter should be about the consistency of cornbread batter; if the batter is too thick, whisk in more water a tablespoon at a time until it reaches the right consistency. Add the serrano, leeks, and cilantro, and stir until everything is well coated in the batter.
6. Heat 8 cups canola oil in a Dutch oven or large, heavy-bottomed pot over medium-high heat to 375°F. Meanwhile, peel and devein 1 1/2 pounds jumbo shrimp if needed. Fit a wire rack over a baking sheet.
7. Batter and fry 5 shrimp at a time: Dip a shrimp in the batter and use your fingers to make sure it has a thick coating of batter and leeks on the outside. Gently drop it into the hot oil. Fry until cooked through and golden-brown, flipping halfway through, 3 to 4 minutes total.
8. Using a mesh spider, slotted spoon, or tongs, transfer the pakora to the wire rack. Immediately sprinkle with a little extra Kashmiri chili powder. To serve, pile the hot pakora on a platter. Drizzle mustard seed oil if using over the raita and serve with the pakora for dipping.