If using the starter culture, stir together the culture and water. Let the mixture sit while you prepare the ingredients—around 10 minutes. If using kefir whey, add it when the recipe calls for culture.
Peel and thinly slice the jicama.
Place the jicama, orange zest and juice, and salt in a 1-quart glass or ceramic container that can be securely sealed.
Add the culture or kefir whey and fill the container with filtered water, leaving 1½ inches of headspace to let the jicama bubble and expand as it ferments.
Seal the container and let it sit on your kitchen counter, out of direct sunlight, for 3 days.
Check the vegetables every day to make sure they are fully submerged in the water. If they have risen above the water, simply push them down so they are fully covered by the water. If any white spots formed because the veggies rose above the water, do not worry. Remember, this isn’t harmful. Just scoop out the vegetables that have the white spots on them and push the rest back under the water.
Storage note: This kraut can be kept in a covered airtight jar in the refrigerator for up to nine months.