Peel the carrots and cut them into 1/4-inch-thick slices.
Put the carrots and dashi into a small pot and bring to a simmer. Cover, lower heat and simmer gently for 4 to 5 minutes or until the carrots are just tender.
Remove cover, add salt and sugar, and turn the heat up a bit. Cook until almost all the liquid has been absorbed. (The little remaining liquid may be used to reheat the carrots, if necessary.)