Prepare the mashed potato by cooking the potatoes in a large saucepan of boiling, salted water until tender; usually 15-20 minutes. Drain and allow to steam for a few minutes before mashing with the crème fraiche, butter and seasoning. Cover and reserve until serving point.
Pre-heat the oven to 190° C.
Use a sharp knife to lightly score the side of the lemon sole fillets that the skin was removed from; this will help to prevent them curling up during cooking. Roll the fillets as you would a cigar, then secure through the middle using a cocktail stick. Melt the butter in a large, heatproof frying pan and sweat the shallot and green beans for 3-4 minutes.
Meanwhile, cut a large round of nonstick baking paper that will cover the surface of the frying pan you are using. Add the lemon sole fillets, then pour in the wine and add a little seasoning. Cover with the parchment and transfer to the oven to finish cooking. Bake for 4-5 minutes until the fish is springy to the touch.
As the fish is cooking, re-heat the mashed potato in a microwave. Brush the insides of an individual ramekin with the olive oil, then fill with the mashed potato. Invert onto serving plates. Remove the fish when it is ready and stir the capers and chopped parsley into the sauce.
Place a couple of lemon sole fillets on top of the mashed potato and spoon the sauce from the pan around the mashed potato and on top of the fish before serving.