Washing leafy greens is a key part of salad making and more generally cooking. There’s several approaches, but my preferred method is:
Fill the 10×10-inch salad spinner basin with cold water then place the basket with greens inside. Gently agitate the mixture, allow it to rest, and then repeat. Pull the salad spinner basket out and let the water drain back into the basin.
Then spin dry in the salad spinner.