Microwave thinly sliced fennel with butter on high for about two minutes until lightly cooked.
Add the fennel and chopped oregano on one side of a piece of foil, lay a fillet of sea bass on top, skin side up adding a little butter and season to taste.
Fold the free side of the foil over the fish and seal the edges.
Oven-bake at 200°C/ Gas Mark 6 for around ten minutes or until cooked through.
