Drain and rinse the jackfruit. Chop off the core (the hard part) and discard. Roughly mash the jackfruit with a fork. Transfer to a bowl, add the sesame paste, soy sauce, and maple syrup. Stir well to coat the jackfruit with the sauce.
Heat a teaspoon of oil in a skillet. Once hot, add jackfruit and sauté for 3-5 minutes. Remove from heat and set aside.
Combine the oat flour, buckwheat flour, ground flax seeds, ground shiitakes, salt, and five spice powder in a large mixing bowl. Add the water and whisk until no clumps remain.
Stir in the shredded cabbage, chopped green onions, coconut bacon, chopped marinated ginger, and jackfruit. Mix well using a wooden spoon or spatula until all the ingredients are coated with the batter. Let it rest 5 minutes.
Heat a large non-stick skillet over medium heat. Once hot, add one tablespoon oil. Pour ⅓ of the okonomiyaki batter into the skillet in a pancake shape. I like to make thick okonomiyaki, a bit less than 1-inch thick. Cover with a lid and cook for about 5 minutes, or until the bottom is golden brown.
Carefully flip, cover, and cook for another 7-9 minutes. Once both sides are golden brown, transfer to a plate, spread about 1 tablespoon of okonomiyaki sauce on top, and drizzle with mayonnaise.
Serve immediately topped with more chopped green onions, and aonori seaweed (optional).
The batter will keep for up to two days, covered, in the refrigerator. You might have to add a few tablespoons of water if it has thickened too much.
Mix all the ingredients together in a small bowl.
Nutritional information doesn't include mayonnaise. It can vary a lot depending on which brand, and how much you are using.