1½ cups plain yogurt
6 medium turnips, trimmed, peeled, and cut into ½" cubes
3 tbsp. peanut or canola oil
2 shallots, peeled and thinly sliced
½ tsp. cumin seeds
2 tomatoes, peeled, cored, and chopped
¼ tsp. cayenne
1. Put yogurt and 1 tsp. salt into a large glass or ceramic bowl and mix together with a wooden spoon until smooth. Add turnips and stir until well coated. Cover with plastic wrap and marinate in the refrigerator for at least 3 hours or overnight.
2. Drain turnips and yogurt in a strainer set over a medium bowl, gently stirring until most of the yogurt has drained into the bowl below. Transfer turnips to another medium bowl. Set turnips and yogurt aside separately.
3. Heat oil in a large nonstick skillet over medium-high heat. Add shallots and cook, stirring frequently with a wooden spoon, until softened, 1–2 minutes. Add cumin seeds and turnips and cook, stirring often, until shallots and turnips begin to brown, about 10 minutes. Add tomatoes, reserved yogurt, and cayenne and cook, stirring occasionally, until turnips are soft when pierced with the tip of a small, sharp knife and sauce has thickened, about 10 minutes more. Season to taste with salt.