While peeling improves the texture of horseradish, it's better to leave it on when you ferment it. We want the nutrients in the skin and the beneficial bacteria that grows naturally on the skin for a better fermentation. If you want to peel yours, It's best to add a quarter cup of starter culture. This can be the juice from a previous ferment or whey from cheesemaking.
Grate your horseradish on the fine side of your grater. Or you can roughly chop the horseradish and use a food processor to chop it. I advise doing so outside where the fumes won't irritate your sinuses or eyes.
Now calculate your salt. You'll be using 2% of the weight of the horseradish in salt. If your horseradish weighs 400 grams, this is your formula: 400 x .02 = 8. You'll be adding 8 grams of salt. If you don't have a scale, add 1½ tsp of salt per pint of horseradish.
Give the paste another whirl in your processor or stir well to incorporate the salt.
Using a funnel, transfer your ingredients into the fermentation jar.
With your pickle packer, a spoon, or your fist, press the ingredients firmly into the jar to eliminate air bubbles and to submerge the ingredients in the brine. If you don't have enough brine to cover the horseradish, add a little water.
Push down the ingredients with a fermentation weight and make sure they are submerged below the surface.
Seal with a fermentation lid or a canning jar lid.
Place a plate under it and leave it for 1- 3 weeks in a darkish corner at about 70-80℉. 3 weeks is the recommended time for long fermentation. But it will be pretty good after a week.
Maintenance and Observing - Just keep a casual eye on your fermentation. You don't need to do anything if it looks ok. It will start to bubble and possibly ooze out of the jar. That is a good sign.
Important: If you're using a regular mason jar lid, don't forget to burp it every day.
Now you can open it, look at it, smell it. If nothing seems off, taste some. If it's good, and you want to store it at this point, take out the weight and add the two tablespoons of vinegar or enough to keep the horseradish covered.
Top with a regular lid and place into the refrigerator. There it will keep for a year. You can also let it ferment for another 2 weeks for the full fermentation benefits.