2 teaspoons yellow split peas
1 tablespoon black mustard seeds (optional)
1 teaspoon hulled black gram beans (urad dal; optional)
3 whole dried red chiles
8 fresh or 12 frozen curry leaves, torn into pieces (optional)
1 teaspoon cumin seeds
1/8 teaspoon asafoetida powder (optional)
1/2 cup unsweetened shredded coconut
3/4 pound green beans, both ends trimmed, beans cut on an angle into 1-inch pieces
1 teaspoon salt, or to taste
1/2 teaspoon saambhar powder or rasam powder (optional)
1 cup water
Combine the oil, yellow split peas, and mustard seeds, if using, in a large wok, kadai, or frying pan over medium-high heat. Cook, stirring, until the split peas turn golden brown. 1 to 2 minutes. (Cover if using mustard seeds—they pop and splatter—and cook until you hear them crackle.) Add the urad dal, chiles, curry leaves, if using, and cumin and cook uncovered, stirring, 1 more minute. (Stand back if using curry leaves; they spit when they hit the oil.) Add the asafoetida, if using, and 1/4 cup of the coconut and cook, stirring, 30 seconds. Add the beans and salt and cook, stirring, 5 minutes. Add the remaining 1/4 cup coconut, the saambhar or rasam powder, if using, and the water. Bring to a simmer, cover, and cook until the beans are tender, about 10 minutes. Uncover and cook, stirring often, until all of the water has evaporated, about 5 more minutes. Taste for salt and serve hot.