Step 1

Bring a pot of water to boil over high. Once the water boils, add the potatoes. Cook until tender, about 10 minutes, then drain in a colander.

Step 2

In a heavy pot, heat the oil over medium. Add the urad dal, cumin and mustard seeds, and fry until cumin seeds are browned and dal is crisp, 1 to 2 minutes. Stir in the cashews, chile and ginger, and cook for another 2 minutes. Add the onion, salt and turmeric, and lower the heat. Cook, stirring occasionally, until the onion is translucent and tender but not browned, about 5 minutes.

Step 3

Tip the cooked potatoes, half the cilantro and 1/4 cup water into the pot, and stir well to coat. As you stir, let some of the potato get mashed. If the mixture seems dry, add a splash more of water. Cook over low, stirring occasionally, until the potatoes are heated through, about 5 minutes, then season to taste with salt. Scrape into a serving dish; top with a generous squeeze of lemon and the remaining cilantro.