In a large skillet or saucepan, heat the vegetable oil over medium heat. Add the chopped onion and cook until it turns golden brown, about 5-7 minutes.
Add the minced ginger, garlic, and green chilies to the skillet, and cook for another 2-3 minutes, until fragrant.
Stir in the chopped tomatoes, ground turmeric, ground cumin, ground coriander, red chili powder, and salt. Cook for about 5 minutes, until the tomatoes soften and the oil begins to separate from the mixture.
Add the water to the skillet, and bring the mixture to a boil. Reduce the heat to low and let it simmer for 10-12 minutes, allowing the flavors to meld and the sauce to thicken slightly.
Gently place the hard-boiled eggs into the sauce, spooning some sauce over the eggs to coat them. Cover the skillet and let it simmer for another 5 minutes, allowing the eggs to absorb the flavors of the curry.
Sprinkle the garam masala over the curry and stir gently to combine. Taste and adjust the salt, if necessary.
Serve the Egg Curry hot, garnished with chopped cilantro, alongside rice, flatbread, or your favorite side dish.