Bring to the boil 1 whole celeriac in skin, simmer and cover for 25 mins. Meanwhile in a bowl add your mirin, garlic paste, ginger paste and dark soy sauce. Remove the celeriac, leave to cool and peel the skin off.
Heat a griddle pan, slice the celeriac into 1 cm thick slices and char on both sides, this will only take 3-4 minutes on either side. In a frying pan add your Wafu glaze and gently heat.
Transfer the celeriac steaks into the glaze, baste and serve with buttered garlic broccoli and some sautéed red onions.