The Food Lab: Better Home Cooking Through Science

To properly wash greens, remove the top of the
salad spinner, leaving the basket in place. Fill it up
with cold water, then submerge your greens and
swish them around for 10 to 15 seconds. Carefully
lift the basket out of the spinner. Any dirt and sand
should be left behind in the bottom. Dump it out, and
repeat the rinsing steps until the water is completely
clear, then spin your greens until completely dry.
Whole head lettuces should be stored intact, but
loose leaves should be washed immediately after
purchase and stored in either their plastic clamshell
container or rolled up in a paper towel and placed
inside a plastic bag left slightly open.