Hiroshima-Style Okonomiyaki

Unlike it's Osaka Counterpart, this has layers of Yakisoba.

150 ml water (⅔ cup minus 2 tsp)
1 tsp mirin
100 g cake flour (¾ cup + 1½ Tbsp; you can make homemade cake flour; or substitute all-purpose flour in a pinch)

8.5 oz green cabbage (about 3 large cabbage leaves)
1 green onion/scallion
2 Tbsp katsuobushi (dried bonito flakes)
4 Tbsp tenkasu/agedama (tempura scraps) (12 g)
2 oz bean sprouts (about 1 handful)
2 Tbsp tororo kombu (optional; dried kelp shavings; you can buy on Amazon or use a sprinkle of kobucha, dashi powder, or kombu dashi powder)
6 pieces sliced pork belly
2 servings yakisoba noodles (pre-steamed; about 11 oz, 310 g)
2 large eggs (50 g each w/o shell)
okonomiyaki sauce (you can make my homemade okonomiyaki sauce recipe)
toppings of your choice (typically aonori (dried green laver seaweed), pickled red ginger (beni shoga or kizami beni shoga), and Japanese Kewpie mayonnaise)