Look for firm, blemish-free bell peppers—either red or green. Organic peppers are ideal, but make sure to scrub off any wax before using. White onions bring the sharpness that’ll balance the sweetness of the corn, so grab the freshest you can find. For celery, pick stalks that are vibrant green and unblemished.

Give your peppers, celery, and onions a thorough rinse in hot water. For peppers, be sure to scrub off any dirt or wax with your fingers or a vegetable brush. Trim and clean your celery, checking for any damaged stalks. Peel your onion before washing to get rid of dirt trapped under the skin.

For bell peppers, remove the stems, seeds, and white pith. Dice them up into small pieces. For a more herbaceous flavor, lean on the green peppers, but if you prefer a milder taste, use red. Chop the celery and onions finely so that each bite will contain a little of everything.

Inspect your jars carefully for cracks and chips—any imperfections here can ruin the canning process. Sterilize the jars by washing them in hot, soapy water, rinsing well, and placing them in the canner. Cover with water, put the lid on, and bring it to a boil. Simmer the lids in a separate saucepan on low to soften the adhesive.

In a stainless steel pan, combine the chopped peppers, celery, onions, sugar, vinegar, celery seed, and pickling salt. Stir well and bring to a boil over medium heat. Once boiling, lower the heat and let it simmer for 5 minutes, stirring occasionally to prevent burning.

Scoop about ½ cup of the mixture out of the pan. Mix in the dry mustard and turmeric until the spices dissolve. Add the spice mixture back into the pot, followed by the defrosted corn (or fresh corn kernels) and stir well.

Bring the mixture back to a boil over medium-high heat. Stir regularly to prevent sticking. Once it’s boiling, reduce the heat and let it simmer for another 5 minutes.

Once your relish is ready, remove it from the heat. Using your jar lifter, carefully remove the sterilized jars from the canner. Place them on a towel or cutting board. Fill each jar using a canning funnel, leaving ½ inch of space at the top. Run a knife around the inside of the jar to release any air bubbles. Wipe the jar rims with a damp paper towel to remove any debris that could interfere with the seal.

Place the filled jars back into the water bath canner. Ensure the jars are covered with at least an inch of boiling water. Process the jars for 15 minutes, adjusting the time for your altitude.

Once the jars have been processed, turn off the heat and remove the lid from the canner. Let the jars rest in the water for 5 minutes to stabilize. Then, using your jar lifter, carefully remove them and place them on a towel or cutting board to cool.

After 24 hours, check the seals by pressing down in the center of each lid. If it’s depressed and doesn’t pop back, it’s sealed properly. If any jars haven't sealed, refrigerate them and consume within a few days.

While your relish is shelf-stable, the salt and vinegar need time to mellow and infuse the flavors into the vegetables. Let the jars rest for at least a week before using them to allow the flavors to mature.