1heat a large saucepan over medium-high heat and pour in the oil. When the oil is hot, add the onion, garlic and ginger and sauté until the garlic starts to brown, 1 to 2 minutes.
Add the cumin seeds, tomatoes and their juices, garam masala, turmeric, coriander, 2 cups water and the 1 tsp. salt and bring to a boil. Reduce the heat to medium-low and simmer, uncovered, for 15 minutes.
Add the potatoes, spinach and chickpeas and continue to simmer until the potatoes are tender, 15 to 20 minutes more.
Season with salt and stir in the cilantro and lime juice. Transfer the curry to a warmed serving bowl and serve immediately.