The secret to a perfect mushroom is to cook it thoroughly, so much so that it releases all its excess liquid and really concentrates in flavour. You want the portobello mushroom quite shriveled for this dish to really work.
2tsp lightly salted butter
1 large portobello mushroom, brushed or wiped clean, and stem removed (keep for cooking)
Melt the butter in a small saucepan, skillet or frying pan, then brush the mushroom on both sides with the melted butter. Season with a little salt and peppery place the mushroom in a small roasting dish and