Sent by Christine
Editor: Try adding 1/8 to 1/4 teaspoon of baking soda to your blanching water. In On Food and Cooking, Harold McGee explains that acidic vegetables (which most of them are to some degree) tend to turn brownish when cooked due to a chemical reaction. Baking soda makes the water alkaline and helps offset the chemical reaction. Be careful, though: too much baking soda or too long in the water can turn the vegetables mushy and give them a soapy flavor.
Also make sure you're cooking the vegetables in plenty of water. This dilutes the acids and slows browning. A 2-gallon stockpot is great, but if your pot is smaller, just blanch the veggies in a few batches.
Readers, any other ideas?
Related: How to Cook Broccoli
(Image: Emma Christensen)