Thinly slice zucchini, red peppers, and onion.

In a large bowl, combine the sliced vegetables.

Sprinkle with kosher salt and toss gently.

Add cold water to cover the vegetables.

Cover the bowl and let it stand at room temperature for 3 hours.

Drain the vegetables using a colander and rinse with cold water.

Drain thoroughly.

In a large pot, combine cider vinegar, 3 cups of water, and sugar.

Bring the mixture to a boil, stirring until the sugar dissolves.

Remove from heat.

Pack the vegetables into sterilized pint jars.

Pour the hot vinegar mixture into the jars, ensuring the vegetables are submerged.

Cool for 30 minutes before sealing the jars.

Label each jar with the date and store in the refrigerator.

Chill for 1-2 days before eating.

Store in the refrigerator for up to one month.