What's the best way to wash lettuce while keeping it crisp? I've been soaking the lettuce head in water and then trying to shake the water off the leaves afterwards, but it doesn't work very well.
Invest in a salad spinner. Soak, spin, store. It increases the shelf life of lettuce and other leafy greens.
For Iceberg lettuce I usually core it first (smash it stem end down on the counter and the core will pull right out) and then turn over under a stream of cool water and let the water run into the head. Turn it core side down and let it drain in a colander or the sink before you then break up/tear apart.
For Leaf lettuce, break the leaves apart and place in a large bowl of sink of cool water and gently swish around OR if it's not muddy or dirty, then leave the head whole and give a good rinse under a gentle stream of cool water. Remove the lettuce leaves from water and drain in a colander or tear apart and drain on absorbent towels, patting gently.
If storing lettuce in plastic bags, spin in a salad spinner and then put in a plastic bag that's lined with a paper towel to absorb excess moisture.
THE BEST method that I have found is to use a "Salad Sac" (no "k" in the name) which is a terry cloth drawstring bag. Wash your lettuce, vegetables, herbs and then simply put in the bag, pull the drawstring tight, shake lightly to help the water bounce off the vegetables and be absorbed into the bag, then place in your vegetable crisper drawer. The bag absorbs the moisture to help maintain the turgor pressure in the vegetables but still allows air to flow and keep them from getting slimy. Earlier this spring I wrote a post on reviving wilted greens and included a picture of the Salad Sac. If you're good at sewing it would be easy enough to make one out of a terry cloth towel.
For your dressing to stick to your leaves they need to be dry. When I buy organic Romaine lettuce (cos in Europe), I break the head apart and clean each leaf with a paper towel. Some dirtier ones may need rinsing and then drying. Most of the time the leafs are clean and it takes no time to do a whole head.
Lettuce is crunchy water, so when the leaves look a bit lifeless, soak them in cold water. Osmosis will bring back to a lively and crispy state. Just dry them well.