This works for any kind of green, although it's really helpful with tiny leaves (like microgreens) that tend to scatter and get lost in the drain and spinach, which needs a very thorough cleaning.
Fill a large mixing bowl with cold water, dump in the lettuce (chop big pieces like romaine beforehand), and then swish and submerge the lettuce until it's clean. Small pieces of dirt and grit fall to the bottom of the bowl. And a bonus is that you likely use less water than you would leaving the faucet running over a head of lettuce as you tried to flip through the leaves. If you've got a large load of lettuce, plug the drain in your sink and use it instead of a bowl.
The photo above is from Saveur, which is illustrating a tip from David Tanis, author of A Platter of Figs. Tanis scoops up his clean lettuce and wraps it in kitchen towels, then stores it just like that in the fridge.
One modification we've made is to use the bowl of our salad spinner as our washing bowl. Instead of using a separate mixing bowl, we fill up the outer container of the salad spinner, submerge our lettuce, then scoop it up and put it in the colander/spinner. Remember: Don't pour the lettuce into the colander; you'll just be washing the dirty water back over it.
• Read the full tip: 3 Chef Techniques, from Saveur
Related: Hot or Not: The Salad Sac
(Image: Andre Baranowski for Saveur)