Weigh it in your hand.
Make sure any potato or sweet potato feels heavy.
2Check the condition.
Avoid any potato with decayed areas (usually at the ends), blemishes or sunken spots. If a potato appears green under the skin, peel it deeply to remove the green part. The rest of the potato should be fine, but the green portion can make you sick. Be sure to remove any sprouts or eyes.
3Size them up.
Choose potatoes of comparable size for uniform cooking.
4Choose the right variety.
Pick russet potatoes (the normal brown kind) for baking or mashing. Russet potatoes turn mealy when cooked and start to fall apart when cut. Select yellow, white or red potatoes for boiling, steaming, roasting or gratins. These potatoes have a firmer texture and won't fall apart when cut. Yellow and red potatoes can also be mashed, but they won't be as fluffy as russets.
5Sweet potato or yam?
Make sure the sharpener or sharpening stone is placed on a flat, stable surface.
6Place the blade in the sharpener.
Choose sweet potatoes with orange, moist flesh (often mislabeled as "yams" in supermarkets). These potatoes have a sweeter taste than those with yellow, dry flesh. Handle sweet potatoes with care, as their skin is delicate. Sweet potatoes don't keep as well as other potatoes; eat them within a week.