Combine shredded cabbage and grated carrots in a large ceramic or glass jar (at least 1 gallon).

In a separate bowl, dissolve kosher salt in spring water.

Pour the salt water over the cabbage mixture, ensuring the vegetables are completely submerged.

Use an inverted small saucer to keep pressure on the cabbage, keeping it submerged.

Cover the container with a clean kitchen towel.

For 3 days, keep the container at room temperature.

Once a day, use the handle of a wooden spoon to poke holes through the cabbage mixture to the bottom of the container. This helps gas escape.

After 3 days, pour a small amount of the liquid from the container into a small bowl.

Stir white sugar into the liquid until dissolved.

Return the sweetened liquid to the container.

Cover the container again, ensuring the vegetables are submerged in liquid.

Keep the container on the counter for 2 more days, again poking holes into the mixture daily to help trapped gasses escape.

After the 2 days, transfer the vegetables and liquid to jars.

Seal the jars.

Refrigerate the jars between uses.