Cut the peeled daikon in half lengthwise (if your daikon is very large, cut the halves in half again so that will be wedges), and into 1/4 inch half-moons. Toss the daikon with 1/4 cup kosher salt in a bowl or colander, and let sit for 3 hours, uncovered at room temperature. Rinse the daikon with cold water and drain any excess water. Pack the salted daikon into a large jar or other airtight container.
Combine 1/2 cup sugar, 1/2 cup rice vinegar, and 1/2 teaspoon turmeric together in a small saucepan and bring it to a boil. Turn off the heat and stir until the sugar is completely dissolved. Cool the vinegar mixture slightly while the daikon sits. Pour the sugar-vinegar mixture into the jar with the daikon. Note that the vinegar mixture should completely cover the daikon. If it doesn't, you may need to mix up a little more vinegar-sugar mixture, using a 1:1 ratio (there is no need to add additional turmeric).
Refrigerate the daikon for at least 3 days before serving. It will keep in the fridge for up to a month.