In general, potassium is found in fruits and vegetables. It has to be spread throughout the day, because high quantities of potassium at once have a laxative effect. The highest concentrations are found in some vegetable concentrates — the densest source in your cabinet is probably tomato sauce. It is present in milk and yogurt but not in cheese.

Potatoes and other starchy vegetables like squash and plantains have significantly more potassium than grains, but it's not necessary to completely give up grains. I usually put a 50/50 potassium/sodium ("Lite") salt on the oatmeal or grits I make for lunch (work requires speed), but I don't bother with it otherwise.