Heat 1/2 tablespoon of the coconut oil in a frying pan over medium heat. Add the bacon and fry until nice and crispy, about 5–6 minutes. Remove from the pan and set aside to cool, then transfer to a large bowl.
Add the cabbage, coconut flour, garlic powder, onion powder and salt to the bowl with the bacon and mix well to combine.
In a separate bowl, whisk together the egg and coconut aminos. Pour the egg mixture over the cabbage mix and stir together to form a thick batter, adding a little extra coconut flour if it seems a bit runny. Preheat the oven to 90C.
Add the remaining 1/2 tablespoon of the oil to the frying pan and melt over medium heat. Drop 2 tablespoons of the okonomiyaki batter into the pan and spread gently with the back of a spoon, then repeat twice more to make a batch of even-sized pancakes.
Cook for 4–5 minutes, or until golden brown and firm, then use a spatula to flip them over and cook for a further 2–3 minutes on the other side until cooked through. Remove from the pan and keep warm in a low oven.
Repeat with the remaining batter, adding another tablespoon of oil to the pan to ensure the pancakes don’t stick to it. Divide the pancakes between plates, dollop on the mayonnaise and sprinkle over the spring onion and sesame seeds.