To prepare miso mixture, combine miso, soy sauce, sugar and mirin in a bowl. Mix thoroughly and reserve.
Over low heat, sauté onions, garlic and bacon for about one minute then, add the green beans and pork belly and cook for about 5 minutes. The bacon and onions will get a little crispy.
Add the crumbled tofu and cook for about 2 minutes to evaporate some of the water content. Stir slightly.
Add the miso mixture, stir, and then add the egg. Stir the eggs around to mix in thoroughly.
Place the green bean mixture on a plate and garnish with sesame seeds and katsuobushi.