Put the onion, oil, garlic, ginger, and salt in a large saucepan. Cook over medium heat, stirring frequently to prevent sticking or burning, until the onion is soft and translucent, about 5 minutes.
Add the cabbage, tomato, and turmeric and stir well to combine. Cover and cook, stirring frequently, for 10 minutes.
Add the chiles, cover, and cook until the cabbage is very tender, about 5 minutes longer.
Season to taste with pepper and additional salt if desired, then serve.