Washing ingredients before slicing removes surface dirt, bacteria, and pesticides, preventing them from being transferred to the cut surfaces and potentially contaminating the entire dish. This practice ensures better food safety and hygiene.
Imagine a piece of produce covered in soil and microscopic organisms. If you slice it first, you're essentially pushing those contaminants into the freshly exposed interior. Washing after slicing is less effective because the water can't reach all the nooks and crannies created by the cuts. Furthermore, water-soluble vitamins can leach out of the cut surfaces during washing, reducing the nutritional value. Washing before slicing removes the contaminants before they have a chance to spread, minimizing the risk of foodborne illness and preserving the ingredient's integrity. This is especially important for ingredients that won't be cooked, such as those used in salads.
For leafy greens, use a salad spinner after washing to remove excess water. This helps dressings adhere better and prevents your salad from becoming soggy.