For okonomiyaki sauce:
Combine flax seed meal and aquafaba and set aside to thicken. Finely chop green onion and cabbage, plus grate the potato. In a large bowl, add green onion, fried shallots, potato and cabbage. Mix. In a separate bowl, add vegetable stock, flour and prepared aquafaba/flax mix. Stir well and pour over the bowl of vegetables. Using your hands, mix everything together really well – there shouldn’t be too much batter covering everything. Let sit for at least 15 minutes. In an oiled frying pan on low heat, place a large handful of the mixture before cooking for 4-5 minutes on each side. Remove okonomiyaki from pan, before covering in okonomiyaki sauce, pickled sushi ginger, more fried shallots, japanese mayonnaise, and sriracha mayonnaise.