SFGate recommends keeping a solution of 1 part vinegar and three parts water in the kitchen for this purpose. For smooth-skinned produce like tomatoes and apples, spray the solution on to coat the exterior thoroughly. Leave it on for about 30 seconds, and then gently rub with your hands and rinse thoroughly. For rough-surfaced and leafy produce like broccoli and spinach, soaking in the solution is better. Let it sit for about 10 minutes or so, and then rub or brush and rinse