Okay, this one isn't that much of a secret, but I do think it's a step that most home cooks skip. Most likely because the level of "green-ness" that a vegetable has in a dish isn't a top priority for someone cooking for their family. But truth be told, it SHOULD be! Everyone has heard "you eat with your eyes first" so if the herb or vegetable on your plate is dull and dark, it doesn't make it look too appetizing. Now, that's not to say you entire meal needs to be wacky, vibrant, and colorful. But when it comes to green vegetables and herbs, I'd say it's a must.
So, how do you keep green things from turning dull and dark? Anyone who has cooked green beans, broccoli, brussels sprouts etc, will tell you that the minute it touches a hot pan or oven, it's vibrancy drops. The best way to ensure your green herbs and veggies stay vibrantly green, is to blanche them before lightly cooking them. Blanching is a technique restaurants use almost every day. It's not only used for green herbs and veggies. It can used as a cooking technique for a variety or different things. No matter what you're cooking though, the technique remains the same. To blanche, begin by boiling and salting some water. You then cook your food ingredient in the boiling water, and then (almost) immediately removing it from the boiling water and place it into ice water. This is called “shocking” it in ice water to keep them from overcooking. The process seals in color, flavor, and texture by halting the enzyme activity that occurs naturally in fruits and vegetables when raw.
It's incredible how this minute-long process can instantly change the look of whatever you're cooking. The brief cooking time activates the chlorophyll in green herbs and veggies and once you shock them in ice water, that bright green color stays put. If you leave your veggie in the water too long, or don't shock it in ice water, you'll just end up with mushy veggies that end up getting dull and dark anyways, defeating the entire technique.
Next time you need to cook green beans, or make pesto, try blanching before doing anything else to it and watch how beautiful the dish ends up. It's a cooking technique that's become a staple in my everyday cooking. Hopefully is becomes one of yours as well soon!