Prepare the ingredients.
Scrape off the unwanted brown spots with a spoon, then use a peeler to slice the ginger thinly.
Sprinkle the thinly sliced ginger with 1/2 tsp kosher salt and let it sit for 5 minutes, then toss into a pot of boiling water and allow to cook for 1 to 3 minutes. If you prefer to retain the ginger’s spiciness, then cook it for only 1 minute; otherwise, keep it in the pot for 3 minutes.
Once cooked, pour the water and ginger into a strainer to drain the water and then spread on a paper towel over a clean dry plate. You can use food plastic gloves to cover your hands as you pick the ginger slices one by one and squeeze them over a Mason jar in order to remove the remaining water.
Boil 100 ml of rice vinegar, 4 tbsp sugar, and 1/2 tsp kosher salt in a small cooking pot for about 60 seconds and wait until you can smell the vinegar evaporating. After 1 minute, turn off the stove, let the pot cool, then pour the vinegar mix from the pot into the Mason jar where you’ve previously placed the sliced ginger. Allow to cool for a few minutes and then close it with the lid and place in the refrigerator.
After several hours, you should be able to see the ginger slices turn slightly pink in color. It'll show more of a pink color after a few days. Use the pink pickled ginger as needed. The way the pickled ginger is preserved is so good that it can last up to a year before spoiling, as long as it's kept in an airtight container and is refrigerated.