The sink is the second germiest spot in your kitchen. To keep microorganisms from populating your sink, you should wash and disinfect the sides and bottom at least once a week, However, if you work with raw meat or are scrubbing dirt off of potatoes, don't wait—wash it immediately.
There are a few ways to clean. Simply use hot water and dish soap. Take a clean sponge and scrub off any chunks of food or pieces of residue you see in there, getting every nook and cranny. you cannot disinfect a surface unless it's already clean, so soap and water should be your first step always. Afterward, you could use a disinfectant wipe—like Clorox Green Works—white vinegar diluted with a little water, or diluted bleach. This works for any surface in your kitchen, but if something will touch food, use vinegar over bleach. If you really want to use bleach, use a 1:50 ratio (a cap of bleach to one gallon of water) and then rinse thoroughly with water afterward.