Whisk together mayonnaise, rice vinegar, and sugar. Set aside.

Whisk together sugar, oyster sauce, ketchup, and Worcestershire sauce until the sugar is dissolved. Set aside.

Shred the cabbage and the carrots. Set aside.

Thinly slice the green onions. Set aside about ¼ of the green onions, preferably more green parts, for sprinkling over the okonomiyaki later.

In a large bowl, whisk together the eggs, dashi or water, soy sauce, and salt together. Slowly add the flour and whisk to obtain a thick, smooth batter.

Stir in the vegetables.

Cut the bacon slices in half.

Heat about ½ tablespoon of the oil in a non-stick or cast iron pan.

Add about 1 cup of batter to the pan and press with a spoon to form a circle of about 15 cm/ 6 inches diameter and about 1.2 cm/ ½ inch thick.

Cover the pancake with some bacon slices, as much as needed to cover the okonomiyaki, depends on the size of the bacon slices.

Cover the pan with a lid, this will help the cabbage get soft.

Turn the heat a bit down, so that the underside of the pancake doesn't get too dark. If you notice that after you have turned the first pancake, adjust the temperature again. The pancakes should be golden brown and not too dark.

Cook the pancake on the first side for 5 minutes until the bottom is golden brown. Flip with a spatula and cook, covered, for another 3-5 minutes or until golden brown.

It is preferable to use two pans when cooking okonomiyaki, you can only cook one at a time, and cooking 6 of them will take quite a while. Using two pans will halve the cooking time.

Place the cooked okonomiyaki on a plate and keep warm in the oven while you cook the rest. Add a little more oil to the pan before starting with each okonomiyaki.

When all the Japanese cabbage pancakes are cooked, brush them with okonomiyaki sauce. Drizzle with the Japanese mayonnaise. Sprinkle with the remaining green onions and with sesame seeds and serve.