Heat up a pot and add oil. When oil is hot, add cumin seeds. When they sizzle, add ginger and let cook for a few seconds. Add onion, 1/4 tsp salt and sauté until soft. Add garlic, green chillies and sauté until golden brown. Add tomatoes, turmeric, chili powder, coriander powder, garam masala, fennel powder and 1 tsp salt. Stir and cook for 1 minute. Cover and cook until tomatoes are soft and oil separates. Stir in between.