Warm the oil in large saute pan or skillet. Add the cumin seeds and sliced onions, and sauté on medium heat until they are lightly golden around the ends, about 8-10 minutes.
Lower the heat and add the garlic, ginger. Sauté for about a min. Add the chopped tomato, ground spices~ turmeric, coriander, black pepper, and red chili. Sauté for a minute, then stir in the zucchini and 2 tbsp water. Stir well to coat the zucchini with spices mixture.
Cover and let cook on medium heat for 7-10 minutes, stirring occasionally. Once the moisture has started to reduce, break the zucchini pieces using the edge of a wooden spoon to disintegrate.
Bring the heat to a simmer, cover and continue to cook for another 10-15 minutes, stirring 1-2 times. If the curry sticks to pan, add a splash of water. Uncover and turn up the heat to high, stir so any extra moisture dries out for about 3-5 minutes. Taste and adjust seasonings.
The curry is done when zucchini is well cooked and moisture has almost disappeared. Garnish with cilantro, if desired. Best eaten with chapati/roti or as an accompaniment with dal and pulao or rice. Enjoy!