Cut cylinders out of the potato slices using an apple corer, simmer in the boiling stock for approx. 10 mins. until just soft. Set aside the leftover potato. Remove the potatoes, keep warm. Simmer the carrots in the stock for approx. 5 mins. until just soft, remove. Set aside the stock, briefly dip the carrots in ice-cold water, peel with a spoon, mix with the butter, toss in the dukkah, keep warm.
Heat the oil in a pan. Sauté the shallot and carrot for approx. 3 mins. Pour in the reserved stock, add the leftover potato, cover and simmer for approx. 30 mins. Puree the sauce, pass through a sieve, season with yuzukoshō, cover and keep warm.
Mix together 1 tbsp of orange juice, vinegar and oil, season with salt, add the carrot, mix. Using 2 tablespoons, shape the carrot salad into balls, plate up.
Dab dry the fish fillets, brush with oil, season with salt. Wrap separately in foil, place on a baking tray.
Cook for approx. 20 mins. in an oven preheated to 70 °C (convection). Plate up the fish fillets, sauce and vegetables. Garnish with the orange segments and saffron.