Roast the peppers on all sides until the skins blister, 8 to 10 minutes on a grill, a stovetop burner or under the broiler. I like to use a grill outdoors.

Cover the roasted peppers with a damp towel for about 15 minutes so the skins slip.

Slip off the skins, working under running water. Wear gloves for hot peppers.

Cut out the stem, seeds and core of each sweet pepper with a paring knife. For hot peppers, cut off the top and remove the seeds.

Prepare a pressure canner: add 2 to 3 inches of water and the trivet, and bring it to a simmer.

Pack the peppers into half pint or pint jars, whole, sliced or diced, leaving 1 inch headspace. Flatten whole peppers before sliding them in (see notes). Add salt using the per-jar amount in the ingredient list, if you like.

Fill the jars with boiling water, keeping 1 inch headspace. Remove air bubbles, wipe the rims, and cap with 2 part lids to finger tight.

Load the jars into the canner, lock the lid, and vent steam for 10 minutes before adding the weight.

Process half pints or pints for 35 minutes at 10 lbs in a weighted gauge canner or 11 lbs in a dial gauge canner, adjusting for altitude (see notes).

Keep the pressure steady the whole time. If it drops, bring it back up and start the timer over.

Turn off the heat and let the canner return to zero pressure on its own. Wait 5 minutes, take off the lid, and leave the jars in the canner 10 minutes before lifting them out.

Cool the jars on a towel, not touching, for 12 to 24 hours, then check the seals. Refrigerate any jar that didn't seal. Sealed jars keep 12 to 18 months on the pantry shelf.