Allow to rest for at least 10 minutes before carving.
- 1 x 800g piece of fillet steak
- 2 tblsp vegetable oil
- 1 large Spanish onion, peeled and sliced
- 2 tblsp butter
- 1 tblsp flour
- 200ml cream
- 1 tblsp Dijon mustard
- salt and pepper
- 4 large flat cap mushrooms
- 1 sprig of thyme, chopped
- 1 bunch watercress, washed and trimmed
- 1 clove garlic
- 2 tblsp olive oil
- Preheat the oven to 140 degrees. Heat a pan with the vegetable oil until smoking. Colour the fillet on all sides until brown and crispy, season, then place on a wire rack in the oven for 30 minutes. This will give you a medium (pink) steak.
- Meanwhile, melt the butter and add the onions and thyme. Cook with a lid on for 20 minutes over a very low heat until soft and add the flour and cook for three minutes before adding the cream, followed by the mustard. Season and set aside.
- Crush the garlic into the olive oil and drizzle over the upturned mushrooms. Season and bake in oven for 5 minutes or so at 180 degrees.
- Remove the beef from the oven and allow to rest for at least 10 minutes before carving. Serve with the creamed onions, the mushrooms, watercress and potatoes of your choice.