How to Make It
In a medium saucepan of boiling water, cook the udon noodles until tender, about 1 minute. Drain. Cut the noodles in half.
Preheat the oven to 350°. In a 10-inch ovenproof nonstick skillet, cook the bacon over moderately high heat until browned and crisp, about 5 minutes. Transfer to paper towels to drain, then coarsely chop.
In a medium bowl, beat 2 eggs with the dashi. Whisk in the flour and salt just until a batter forms.
In the skillet, melt 1 1/2 tablespoons of the butter. Add the mortadella and stir-fry over moderately high heat until lightly browned, about 2 minutes. Add the cabbage and carrot and stir-fry until just wilted, about 1 minute. Stir in the udon and pour the batter into the skillet. Cook until the okonomiyaki is browned on the bottom and set around the edge, about 6 minutes. Transfer to the oven and bake for about 7 minutes, until the okono-miyaki is cooked through.
Meanwhile, in a small skillet, melt the remaining 1/2 tablespoon of butter. Crack the remaining 1 egg into the skillet and cook over moderate heat until the white is firm and the yolk is runny, 3 to 5 minutes.
Invert the okonomiyaki onto a platter. Top with the fried egg and chopped bacon. Drizzle with Kewpie, Sriracha and hoisin, garnish with sliced scallions and furikake and serve.