Fillet steaks with mustard sauce

596g (1lb 5oz) new potatoes, scrubbed

Low-calorie cooking spray

Tiny sprigs of rosemary Sea salt

For the sauce

2 shallots, peeled and chopped

2tsp mustard powder

340ml (12fl oz) beef stock

1 level tbsp wholegrain mustard

312g (11oz) mixed mushrooms (button, chestnut, shiitake), sliced

6tbsp fat-free natural yogurt

Handful of fresh parsley, finely chopped

Salt and freshly ground black pepper

For the steaks

4 lean beef fillet steaks

2tbsp crushed mixed peppercorns

Wilted spinach, to serve

1. Pre-heat the oven to 200°C (gas mark 6). Cut small slices into each potato at regular intervals, making sure not to cut right through. Place the potatoes on a baking sheet and spray with low-calorie cooking spray. Tuck the rosemary sprigs into some of the slices. Sprinkle with sea salt and cook in the oven for 10 mins.

2. Remove from the oven, turn the potatoes and cook for a further 30-40 mins, or until cooked through. Set aside and keep warm.

3. Meanwhile make the sauce; place the shallots, mustard powder, stock and mustard into a small pan. Whisk to mix well and bring to the boil. Reduce the heat, add the mushrooms and simmer for 8-10 mins. Remove from the heat and stir in the yogurt and chopped parsley. Season well and keep warm.

4. Season the steaks with the crushed peppercorns and some salt. Spray a non-stick frying pan with low-calorie cooking spray and place over a high heat. Cook the steaks for 5-6 mins on each side, or until cooked to your liking.

5. Divide the potatoes and steaks between four warmed plates, drizzle over the sauce and serve with the wilted spinach.