Rinse, peel and shred the carrots.
Put the carrots in a bowl and sprinkle the salt over them.
Let the carrots sweat for at least 30 minutes.
Rinse off the salt and drain the carrots well.
Add the vinegar, mirin, dashi, sugar and water to a small pot and bring the mixture to a boil.
Remove the pot from the heat and add the carrots. Cook with the heat of the marinade, tossing the carrots constantly, for 30 seconds.
Put the carrots and marinade in an airtight container.
Refrigerate the carrots for at least 30 minutes.
Drain the carrots, toss with the black sesame seeds and serve.