Steam the potatoes until they are tender (about 20~25 mins. depends on the size). While they are still hot, peel them.
Heat a pot over medium heat. Add mirin and then dashi, sugar and heat until cooked (about 30 seconds). Put soy sauce into it and heat.
Dust the potatoes with flower, brushing off any excess and plunge in the oil. Deep fry until the surface becomes golden brown, and drain off the oil and arrange on a plate.
Pour in the heated broth and topped with grated daikon radish, and sprinkle with shichimi spice powder.