Bring a large pot of salted water to a boil. Boil the eggplant for about 4 minutes and transfer to an ice bath or cool with cold water in a strainer. Set aside.
Heat the oil over medium heat in a large, nonstick sauté pan. Add the cumin seeds and fry until they become fragrant, about a minute. Add the onions and cook until transparent, about 5 to 8 minutes.
Add the potatoes and turmeric, seasoning with salt and pepper. Mix well so that the potatoes and onions take on a golden-orange hue, and separate any potato slices that stick together. Fry, stirring often, until the potatoes brown and soften, about 10 to 12 minutes.
Add the garlic, ginger and fresh chilies. Cook just until fragrant, about a minute. Add the eggplant and broth and adjust the seasoning. Reduce the heat to medium-low and simmer until the eggplant and potatoes are tender, about 12 to 15 minutes. Just before you remove the pan from the heat, stir in the tomatoes, cilantro and green onion. Check seasoning and serve hot, over rice.