Cut the tofu into small pieces. Bloat each with paper towels and coat with corn starch. Set aside.
Bring all the ingredients of tentsuyu sauce to gentle simmer in a small sauce pan. Do not bring to a full boil.
Heat up the oil in a wok a frying pan and deep fry to tofu until they turn light brown or crispy. Please take note that the corn starch coating will not turn to golden brown easily. Remove the deep-fried tofu and drain the excess oil on a plate lined with paper towels.
To serve, place a few pieces of tofu in a small bowl and pour some tentsuyu sauce on the tofu. Garnish with some grated daikon, chopped scallions and dried bonito flakes. Serve immediately.
You can get my dashi recipe from my Nabe (Yosenabe) post.
If you don't want to make dashi from scratch, you can use bottled dashi shoyu or dashi soy sauce from Japanese market and add mirin, sake, and sugar to taste to make the stock.