1. Heat the oil in a large saucepan over medium-low heat. When it shimmers, add the onion, fresh ginger (if using), and garlic and cook, stirring occasionally, until the onion is translucent but not browned, about 5 minutes.
2. Add the coriander, cumin, cayenne, and ground ginger (if not using fresh) and cook for 1 minute.
3. Add the chickpeas, water, diced tomatoes, and salt to taste and raise heat to medium. Simmer uncovered (if it spatters too much, cover it partially) until the sauce has thickened, 5 to 10 minutes.
4. Remove from heat, then stir in the chopped cilantro, garam masala, lemon juice, and salt to taste.
5. Serve over brown rice and top with a spoonful of yogurt and chutney, if desired.