Though this Indian classic is often made with spinach, the best renditions we have eaten use mustard greens instead, or in combination with spinach, kale, or turnip greens. Usually, the greens are pureed after they are cooked, but we prefer the rustic texture of chopped greens (and there are fewer items to clean). For a long-simmered curry, see Lamb Saag. If desired, substitute 6 ounces store-bought paneer for homemade.

Bring to a boil in a medium heavy saucepan:

Remove the pan from the heat and add:

Stir until the milk curdles and separates into bits of solid curd floating in the liquid whey. Let stand for 5 minutes. Line a fine-mesh sieve with a double layer of cheesecloth and set over a bowl. Ladle the curds and whey into the sieve and let stand until cool enough to handle. Pull the edges of the cheesecloth together over the curd and squeeze out as much liquid as possible. Flatten the curd, still in the cheesecloth, to a thickness of ½ to 1 inch. Set it on a plate and top with another plate. Weight with a can and let stand for 20 minutes, then cut the paneer into ½-inch cubes.

Coarsely chop:

Heat in a large nonstick skillet over medium-high heat:

Add the paneer cubes and cook, shaking the skillet every now and then to turn the cubes, until golden brown, 3 to 4 minutes. Transfer the paneer to a plate. Add to the oil remaining in the skillet:

Cook, stirring, until the mustard seeds start to pop, about 1 minute. Add and cook until softened, about 5 minutes:

Add and cook 1 minute more:

Add as much spinach as will comfortably fit into the skillet, cover, and cook until wilted enough to add more spinach. Add a few more handfuls and repeat until all the spinach is wilted. Cook, uncovered, until all the water is evaporated. Fold in the paneer and serve immediately.