[header] How to keep cooked broccoli bright green [title] Be careful not to steam green vegetables. [step] Green vegetables contain chlorophyll, when chlorophyll is cooked, it produces carbon dioxide. Since you have to cover the vegetables to steam them, the chlorophyll turns a drab, grayish color. 
You can prevent this by boiling the greens, in salted water. [title] Use a large amount of water, then add salt.