Step 1

Heat vegetable oil in a large saucepan or small pot over medium-low. Cook onion, stirring occasionally, until golden brown and very tender, 15–20 minutes.

Step 2

Meanwhile, toast coriander seeds and cumin seeds in a dry small skillet over medium heat, tossing occasionally, until slightly darkened and fragrant, about 2 minutes. Transfer to spice mill or mortar and pestle and let cool; finely grind.

Step 3

Add spice mixture, garlic, ginger, garam masala, turmeric, and cayenne to pan with onion. Cook, stirring, until fragrant, about 3 minutes. Add tomato, chickpeas, tomato paste, and 2 cups very hot water; season with salt and pepper. Cover pan; simmer, adding up to 1 cup more hot water if chana masala looks dry, until chickpeas are very tender and sauce is flavorful, 45–60 minutes.

Step 4

Stir cornstarch and 2 tsp. water in a small bowl, then stir into chana masala. Simmer just until thickened, about 1 minute. Remove from heat and stir in olive oil. Season with more salt if needed.

Step 5

Top chana masala with cilantro and serve with rice and/or flatbread.