Cut the pork belly into 4cm pieces and season with salt and pepper.

Slice the onion into 7mm thin slices and chop the mitsuba into 2cm pieces.

Heat salad oil in a frying pan over medium-low heat, add pork belly, and cook until the color changes. Add onion and sauté until translucent.

Add curry powder and stir until the powder is well incorporated. Pour in mentsuyu and water, bring to a boil, cover, and simmer on low heat for about 5 minutes.