Heat 1 tablespoon of sesame oil in a non-stick fry pan over medium hot. Fry the tofu slices 1-2 minutes each side. Remove from the pan and set aside. In the same fry pan, add 1 tablespoon of sesame oil. Fry the mushroom 1-2 minutes each side. Coat them in a little of the reserved marinade.
Meanwhile, prepare the lightly pickled crunchy vegetables. Sprinkle the white vinegar on the cucumber, carrot and radish.
Heat the bao buns according to the packet instructions.
Open the bao bun and sandwich the tofu, mushroom and pickled vegetables with some mayonnaise. Top with spring onions, coriander, walnuts and some more marinade.