Wash carrots and potatoes thoroughly. Cut the unpeeled potatoes into 2cm cubes and place in a bowl. Salt, pepper and mix with the olive oil. Spread the potato cubes on a baking sheet lined with baking paper and bake for 20-25 minutes at 180 degrees until golden brown. Leave some space on the baking sheet for the barramundi fillets.
Peel the carrots and cut into thin slices. Put in a saucepan, add a little salt and cook for about 10-15 minutes until soft. Drain the rest of the water, add the butter to the carrot slices and let melt.
Carefully bring the cream with the vegetable stock and mustard to the boil briefly and add some water if necessary.
Rinse the fish fillets, pat dry, add salt and pepper. Wash the lemon with hot water and cut into slices. Place slices on top of the fillets and then place the fillets skin down next to the potatoes on the baking sheet. Cook the barramundi fillets for 12-15 minutes, until the fillets are no longer translucent.
Spread the potato cubes, carrot slices and the sauce on plates. Place the barramundi fillets in the saucepan. Sprinkle everything with a little chopped parsley. GOOD APPETITE !