Heat oil in a large skillet. Add onion, garlic, and ginger and saute over medium heat until browned, about 5 minutes. Turn heat down to medium-low and add the coriander, cumin, cayenne, turmeric, cumin seeds, paprika and garam masala. Cook onion mixture with spiced for a minute or two, then add the tomatoes and any accumulated juices, scraping up any bits that have stuck to the pan. Add the water and chickpeas. Simmer uncovered for 10 minutes, then stir in salt and lemon juice.