When you get fresh veggies from the supermarket, you'll want to give them a good scrub down before cooking them. Sure, you can use plain water, but if you're trying to get the grit out of the nooks and crannies of leeks, or you're dealing with an unwashed head of lettuce, don't spend money on a commercial vegetable wash. Make your own.
The recipe is pretty simple: mix a few tablespoons of bicarb soda stirred into a cup or two of water. Enough to mix it up, but not enough to completely dissolve the mixture. Pour the whole thing into a spray bottle if you want to go that way, or pour it into a mixing bowl you can use to scrub your fruits and veggies. Ideally you'll have a little grit left in the water so you can get the surface of your produce good and clean, and then rinse them under tap water to make sure everything -- bicarb soda and any dirt you've loosened up -- all wash away.
Have your own recipe? Just prefer plain tap water or vinegar? Let us know in the comments below.