Heat up enough vegetable oil for deep frying in a pot.
Place flour, 2 beaten eggs and panko breadcrumbs in three separate shallow bowls
Dip each chicken breast into the flour, followed by the beaten eggs and finally, the breadcrumbs.
Deep fry for 4-5 minutes, until cooked through. Set aside to drain, then slice.
In a shallow pan, heat 1 tbsp of vegetable oil over a medium heat. Saute the yellow onion until softened.
Add dashi stock, soy sauce, sugar and mirin and simmer for 1-2 minutes.
Pour in the beaten eggs in a circular motion, and turn off the heat.
Place the sliced chicken katsu into the centre, and pour over the cooked rice. Serve.