1. In a large, deep frying pan, heat the oil over moderate heat. Add the onions and cook, covered, stirring occasionally, for 5 minutes. Uncover and cook, stirring occasionally, until the onions are very soft, about 5 minutes longer.
2. Stir in the turmeric to coat the onions. Stir in the broccoli, tomatoes, water, and salt and bring to a simmer. Reduce the heat and simmer, covered, until the broccoli is tender, about 10 minutes.