6 medium shallots, peeled and quartered lengthwise
2 medium cloves garlic, finely chopped
1-inch piece ginger root, peeled and grated (about 1 tablespoon)
1 small red bell pepper, stemmed and thinly sliced
2 medium tomatoes, quartered
8 fingerling potatoes (may substitute very small new potatoes)
4 spicy dried red chile peppers
1 teaspoon kosher salt, plus more as needed
2 tablespoons vegetable oil
3/4 cup large whole cashews, roasted and unsalted
1 teaspoon black mustard seed (see headnote)
6 to 8 fresh curry leaves (optional; see headnote)
1 teaspoon ground turmeric
1 teaspoon light or dark brown sugar
14 ounces (1 can) reduced-fat coconut milk
1 lime (optional)
Heat the oil in a heavy-bottomed medium saucepan over medium heat. Add the cashews and shallots; cook for 5 minutes, stirring often, until the nuts just start to brown.
Add the mustard seeds and curry leaves to taste, if using; cook for a few minutes, until the seeds start to pop and crackle. Add the garlic, ginger, dried chile peppers, red bell pepper and turmeric. Cook for 2 minutes, stirring, until aromatic, then stir in the brown sugar.
Add the tomatoes, potatoes and coconut milk. Once the milk is heated through and is bubbling at the edges, partially cover and cook for 20 minutes, stirring occasionally and reducing the heat as needed if the curry bubbles too vigorously or appears to be burning on the bottom. The shallots and potatoes should be tender. Taste, and adjust the seasoning as needed. Remove the chile peppers.
Divide among individual bowls; if you haven’t used curry leaves, cut the lime into quarters and sprinkle each portion with lime juice.
Serve hot, with basmati rice.