Place all of the sauce ingredients except the corn flour into a medium size pot and bring to the boil on high heat. Once boiling, uncover and simmer on low heat for around 40 minutes or until the broth has a deep flavour. You want the mushrooms to be cooked through but stay nice and firm to touch.
Whilst your sauce is cooking, combine all of the pickle ingredients except the carrot and ginger in a small saucepan and bring to the boil. Put your carrot and ginger in two small containers and once the pickling liquid has boiled, remove from the heat and divide between the carrot and ginger. Set aside and allow to pickle.
To create the emulsion, combine the silken tofu, vinegar, mustard and ginger in a cannister that will fit the stick blender. Season with salt and pepper. Start belding and add a teaspoon of the Grapeseed Oil at a time as the sauce thickens. It may not get as thick as a traditional mayonnaise or emulsion, but that's OK, it still works great on this dish. Set aside.
To create the batter for your vegan Okonomiyaki pancakes, in a medium to large mixing bowl, whisk together the flax seed meal and water to create a paste. This is your egg replacer and will bind everything together. Whisk in all of the other ingredients except the carrot to form a batter, then stir in your carrot. Set aside.
By now your broth should be tasting pretty good. If you're happy with the depth of flaour in the liquid, strain it into a small saucepan and boil on high so that it reduces. Keep the vegetables aside so that we can use the mushrooms on the finished dish.
Once the sauce has reduced by about half, which may take around 15 minutes, create a paste with the cornflour and a dash of tap water. Mix this into your sauce and allow it to thicken, whisking continuously as you would with a gravy. After a couple of minutes, if it's thick, remove from the heat and allow to cool slightly, it will continue to thicken as it cools. If it's not thickening, add a touch more cornflour (make sure you turn it into a paste first to avoid lumps).
Heat a large non stick pan on medium heat and add a little oil and nuttalex or vegan butter. Once hot, scoop 1/4 of the batter into the pan and shape into a disk. If you have pancake rings use 10cm ones. Repeat so that you're cooking 2 pancakes at a time, if your pan is big enough.
Cook for around 3 minutes each side, checking to ensure they aren't burning and only flipping once if you can.
Remove from the pan and sit on paper towel for 30 seconds to absorb excess oil.
To serve, start with a pancake, pour some emulsion over it, place some mushrooms, then your pickled ginger and carrot, creating a little flavour garden on top of the pancake. Finish with a good drizzle of the Okonomiyaki sauce.
Enjoy with some rice or a potato croquette.