Heat oil in a nonstick skillet over high heat. Add onions, and sauté until lightly golden, about 8-10 minutes.
Lower heat to medium, and add garlic, ginger and cumin seeds. Sauté until the raw smell of the ginger and garlic disappears, about 20-30 seconds. Add tomato, salt, coriander powder, black pepper and cayenne. Sauté for 1 minute, then stir in zucchini and 1/4 cup of the broth. Mix well, ensuring the zucchini is well coated.
Cover, and let cook for 7 minutes, stirring once. Once most of the broth has dried up, use a wooden spoon to break the zucchini into pieces. Add jalapeño and turmeric, and sauté for a few minutes.
Lower heat to medium-low, cover, and continue to cook for 15-20 minutes. Stir once half-way. If you’re afraid it will stick to the pan, add remaining 1/4 cup broth. Uncover, and stir well. Taste and adjust salt.
When zucchini is very soft and well cooked, turn off heat and serve.