4 cups water
2 cups long grain rice, rinsed and drained
1/2 teaspoon salt, or to taste
2 tablespoons vegetable oil, divided
1/4 cup coarsely chopped cashews
7 small dried chile peppers
1 teaspoon mustard seed
1 teaspoon cumin seed
10 fresh curry leaves
1 teaspoon ground turmeric
1/4 cup fresh lime juice
2 tablespoons tamarind paste
1 cup plain yogurt