Potatoes are best stored in a cool, dark environment, but the refrigerator is too cold. The chill starts to break down the starch in the potatoes, causing a gritty texture that is unpleasant to eat.
The starch also begins to turn to sugar in the fridge, further impacting the flavor.
Onions will spoil more quickly in the refrigerator than on the counter. They’ll get moldy and mushy before you know it. It’s best to store onions at room temperature, but keep them out of direct sunlight.
Once the onion is peeled and cut, you will want to refrigerate it. Just place it in a sealable bag and store it in the vegetable drawer.