Peel, wash and cut the potatoes into round slices. Place them in a pyrex baking tray, season with salt and pepper, sprinkle with the oregano and pour half of the lemon juice over them.

Add the water and as much oil as you like. Mix so that the liquids are evenly distributed. Place the baking tray on the bottom rack of the oven and bake at 200°C for half an hour or until the potatoes start to get golden brown. If necessary, add a little water.

Remove the baking tray from the oven, place the fillets on top of the potatoes, pour the rest of the lemon juice on top as well as the wine.

Brush the sole fillets with the mustard, sprinkle with oregano and season with salt and pepper. Add just a little more oil.

Place the baking tray back into the oven and bake for an additional 20'.