Place sweet potatoes in a large stockpot and steam or boil them for 15-20 minutes.

Turn off the heat, remove from the pot and allow them to cool until they're no longer too hot to handle.

While the potatoes are cooling, prepare a pressure canner by adding a few inches of water to the bottom, along with the canning trivet, and bring it to a low simmer on the stove.

In a separate pot, prepare a canning syrup (see notes) or plain water, and bring it to a boil.

While the canner is heating, peel the sweet potatoes. Their skins should come off easily with your fingers now that they're partially cooked, but you can also use a knife.

Slice the sweet potatoes into a uniform size and pack into canning jars leaving 1-inch headspace. (Very small sweet potatoes may be peeled and canned whole).

Pour the boiling water (or canning syrup) over the sweet potatoes in the jars, still maintaining a 1 inch headspace.

Debubble jars, adjust headspace, wipe rims and seal with 2 part canning lids.

Load the canning jars into the pressure canner and cap up the lid.

Allow steam to vent for 10 minutes to ensure that the chamber is completely full of steam, then apply the canning weight and bring the pressure canner up to pressure. (10 pounds pressure at sea level with a weighted guage canner, see notes for other canner types and elevations.)

Process the sweet potatoes at pressure for 90 minutes for quarts and 65 minutes for pints.

Once the canning time has elapsed, turn off the heat and allow the canner to cool to room temperature (and 0 pounds pressure).

Once cooled, unseal the canner and remove the jars to a towel on counter. Check the seals and store any unsealed jars in the refrigerator for immediate use.

Properly canned sweet potatoes with intact seals should maintain quality store at room temperature on the pantry shelf for 12-18 months.