600g large baking potatoes, peeled and cut into fries
Low-calorie cooking spray
2 shallots, finely diced
10 peppercorns
4 tbsp finely chopped fresh tarragon leaves
4 tbsp chopped fresh flat-leaf parsley
1 tbsp white wine vinegar
150ml vegetable stock
2 level tbsp extra-light mayonnaise
100g fat-free natural fromage frais
4 tbsp drained and rinsed chopped capers
4 lean beef fillet steaks, visible fat removed
500g baby spinach
1 Preheat your oven to 200C/fan 180C/gas 6. Boil the fries for 1-2 minutes, then drain well. Spread on a non-stick baking tray in a single layer and spray with low-calorie cooking spray. Season and bake for 12-15 minutes, or until golden.
2 Meanwhile, put the shallots, peppercorns, 1 tbsp tarragon, 1 tbsp parsley and the vinegar and stock in a small saucepan, and stir together. Bring to the boil, then allow the liquid to reduce by a third (this should take about 6-8 minutes). Strain into a heatproof bowl, discarding whats left in the sieve, and leave to cool slightly.
3 Once cooled, whisk in the mayo and fromage frais. Season with a little salt, then stir in the capers and remaining herbs. Set aside.
4 Season the steaks and spray lightly with low-calorie cooking spray. Preheat a non-stick griddle or frying pan until smoking hot, then cook the steaks for 2-3 minutes on each side for rare, 4-5 minutes on each side for medium, or 6-7 minutes on each side for well done.
5 While the steaks are cooking, boil the spinach for 2-3 minutes, or until wilted, then drain well and season.
6 Dry the steaks on kitchen paper before transferring to plates. Serve with the spinach, frites and a quarter of the Barnaise sauce per person.