what is the best way to store letuce in the fridge?
- should I store it in a air thight bag on in an open bag?
- should I wash and cut it first?
- should it be stored wet or patted dry?
It depends on what type of lettuce it is -- part of the issue is that if the lettuce is touching plastic, it will rot quicker, so I wrap it in paper towels, then bag it (but not sealed), and keep it in my crisper.
For whole heads of lettuce (iceburg, butter, red leaf, etc), I just wrap the whole thing in dry paper towels, then shove it back into the bag from the grocery store or farmer's market. I then pull off leaves as I need it, and re-wrap it. It stores for well over a week this way.
For mescalin mixes, arugula, or other individual leaves, I'll wash them, dry them, then unroll enough paper towels to spread the leaves on, then roll up the whole thing, and bag the roll (again, not sealed), and keep it in my crisper. I can probably get a week out of it this way.
(all times assume you're not buying from a store where it's been sitting on the shelf too long before you buy it; I get my lettuce when I can from the local farmer's market)
So, to answer the specific questions:
For a head of lettuce, I have a special Tupperware that is specifically designed for storing lettuce. It keeps the lettuce fresher longer! Definitely worth the money!
With lettuce, parsley, or green leaves in general, I care for three things:
Avoid mechanical damage
Even tiny fractures rot much faster, if the cell fabric is intact, it does a good job of preserving the lettuce. Specifically, this means:
Store neither too dry, nor too wet
I usually buy fresh heads of lettuce from local suppliers and prepare them for storage right after coming home. I can easily keep the leaves for a week and longer. In the winter, when the lettuce comes from Spain or France (I'm in Germany), the results are not as good, because the lettuce already had quite a journey. I then prefer field salad and the like, they are available locally way past December, and also store very well.
I have just found the transcript of a Good Eats episode about lettuce storage. It's close to Joe's answer but they say the lettuce should be kept in an air tight bag with air sucked out.
In short they say:
See senes 9-10-11 of http://www.goodeatsfanpage.com/Season1/Salad/SaladTranscript.htm