Heat 2 tbsp oil in a large deep skillet or Dutch oven over medium-high heat. Add the whole cumin seeds and let them sizzle for 20 to 30 seconds until aromatic and slightly darkened.

Add the diced onion and cook for 5 to 6 minutes, stirring frequently, until golden brown around the edges. Stir in the minced garlic, ginger, and green chili. Cook for 60 seconds until fragrant.

Reduce heat to medium. Add ground coriander, ground cumin, turmeric, Kashmiri chili powder, and salt. Stir constantly for 30 seconds to bloom the ground spices in the oil.

Add the canned diced tomatoes with their juices. Cook for 3 to 4 minutes, crushing the tomatoes with your wooden spoon, until the liquid reduces and oil begins to bead at the edges.

Pour in the rinsed chickpeas and 1 cup of water or vegetable broth. Bring to a gentle boil, then reduce heat to medium-low.

Using the back of a sturdy wooden spoon or potato masher, crush about one-third of the chickpeas directly against the bottom of the pan. Stir well; this releases starch and naturally thickens the curry gravy.

Simmer uncovered for 6 to 7 minutes until the gravy is thick, cohesive, and coats the chickpeas.

Stir in garam masala and lemon juice (or amchur). Simmer for 1 final minute. Remove from heat, garnish generously with fresh cilantro, and serve with basmati rice, bhature, or warm naan.