Serve with cooked rice or even better, warmed naan or other flatbread for scooping. This Indian vegetarian eggplant recipe doubles easily if you're serving a crowd or just love leftovers.
Roast eggplant directly on a gas burner or under a broiler, turning occasionally, until charred all over and very soft, about 12 minutes. Let cool 10 minutes. Scoop out flesh and discard skin. You should have about 2 1/2 cups eggplant.
Grind onion, ginger and garlic together in a food processor to form a paste. Heat oil in a large skillet over medium-high heat; add butter and melt. Add cumin; when it sizzles, stir in onion paste, and chiles. Cook, stirring frequently, until translucent, about 3 minutes. If onion is sticking to pan, stir in 3 tablespoons water and scrape up browned bits, then stir in tomatoes.
Cook, stirring frequently, until tomatoes are broken down, about 5 to 7 minutes. Add turmeric and stir to combine, then add eggplant, stirring until heated through.