Crisp Okra in Yogurt Sauce

Heat 6 tablespoons oil in a 12-inch heavy skillet over medium-high heat until it shimmers. Fry okra, stirring occasionally, until well browned and crisp, about 15 minutes. Transfer to paper towels to drain and season with 1 teaspoon salt. Purée coconut, 1/2 teaspoon mustard seeds, cumin seeds, and chile in a blender or food processor with enough water (1/2 cup to 1 cup) to form a fine paste. Bring coconut paste and yogurt to a bare simmer in cleaned skillet, stirring, then remove from heat. Heat remaining 1 tablespoon oil in a small heavy skillet over medium-high heat until it shimmers, then cook remaining 1/2 teaspoon mustard seeds and red pepper flakes until mustard seeds begin to pop and/or turn gray. Add curry leaves (if using), covering skillet immediately as the leaves crackle for a few seconds. Stir spice mixture into coconut mixture in skillet, then stir in fried okra, then lemon juice. Season with salt.