Japanese Pickled Ginger (Gari)

Steps

1. Use an inverted spoon to scrape off the thin, papery bits from the ginger. To cut super thin slices, use a mandoline or very sharp knife. Cut across the grain and aim for nearly see-through pieces.
2. Transfer the ginger to a saucepan or heatproof bowl. Toss with the 1 1/2 tablespoons of sugar and salt. Set aside for 30 minutes to reduce its harshness.
3. About 10 minutes before the ginger finishes mellowing out, bring a kettle of water to a boil. When the ginger is done, pour the just-boiled water over the ginger. Use enough water to cover the ginger. Gently stir and let sit for 20 seconds to further reduce the harshness. Dump into a mesh strainer. Don’t rinse. Shake a few times to expel water, then transfer into a 2-cup capacity glass jar.
4. In a saucepan (it's fine to reuse the one you just used!) over medium heat, bring the remaining 1/4 cup (50g) of sugar, vinegar, and kelp to a boil. Stir a few times to dissolve the sugar. Remove from the heat and pour into the jar of ginger.
5. Push down with chopsticks or a spoon to submerge. Cool, uncovered, then cap and refrigerate. Depending on the ginger, it may be ready to eat in 1 to 3 days. Taste and see. After 3 days, if the ginger is not sweet enough, add sugar by the 1/2 to 1 tablespoon; or if it is too sweet, add vinegar by the 1 tablespoon. Then let it mature in the fridge for a few days before eating. Keeps well in the refrigerator for about 1 year.