I love salad, but I really wanted my greens to be crisp and snap like a salad in a restaurant. Here’s the way I developed that works for me.
First wash the greens well in cold water. Yes, even if the container says pre-washed. It’s not so much about making sure the greens are clean (though certainly if you have that concern with pre-washed greens, this step addresses that concern); it’s more about making sure the greens are hydrated and that the moisture will help keep them snappy during storage. I use the basket of my salad spinner for this job If I have a lot of greens to handle, or large greens like chard, I may fill up a pan in the sink (I never use my sink directly – sinks are one of the dirtiest places in the house).
Then use a salad spinner to spin off excess water. I like my http://OXO Good Grips Salad Spinner, Large, Clear because I can push the spin handle on top, rather than have to rotate a handle around.
Once most of the water is spun off, I turn out the greens onto a cotton/linen dish towel. Don’t use one that can have lint on it (personal experience). As you spread the greens out on the towel, remove anything that looks brown, or is starting to spoil. Roll up the towel lightly to remove more water that may be clinging to leaves.
Lastly I use http://Debbie Meyer GreenBags Freshness-Preserving Food/Flower Storage Bags (Various Sizes, 20-Pack) to store greens in the fridge. I place a folder paper towel in the bag first (it also helps absorb any excess moisture), add the greens, push our excess air, and use a clip to seal the bag.
I find my salad greens will stay fresh and really crisp for a week or longer this way.
I have found that you need to identify the coldest part of your fridge, and NOT put the greens there. I have actually had some greens freeze in this area. They need to be cold, but not frozen! A vegetable bin will work as well.
This technique works for individual kinds of greens, or wash and make your own mix and have it all prepared in one green bag – just open and pull out for instant salad mix. I do not recommend adding other vegetables, like shredded carrots, to this bags of greens.