Côte de boeuf

1.Cut potatoes into thin chips and soak in a bowl of cold water for 1 hour to remove excess starch (this makes for crisper chips).

2.Heat oil in a deep-fryer or large deep saucepan to 150C. Drain potato chips, pat dry with a clean tea towel, then deep-fry in batches until softened but not coloured (7-8 minutes). Drain on a tray lined with paper towels.

3.For béarnaise, simmer vinegar, wine, shallots and peppercorns in a saucepan over medium heat until reduced by half (1-2 minutes). Strain (discard solids) into a heatproof bowl placed over a saucepan of simmering water, then add egg yolks and whisk continuously until pale, frothy and thick enough to hold a ribbon when drizzled from the whisk (3-4 minutes). Remove from heat and gradually add butter a drop at a time at first and then pour in a thin steady stream, whisking continuously to emulsify. Season to taste, stir in tarragon and keep warm.

4.Heat a char-grill pan or barbecue to high heat. Brush steaks with a little olive oil and season to taste with salt. Grill steaks, turning occasionally, until cooked to your liking (12-15 minutes for medium), then set aside to rest for 10 minutes.

5.Meanwhile, reheat oil in deep-fryer to 180C, add chips in batches and deep-fry, turning occasionally, until golden brown (1-2 minutes). Drain on paper towels, season to taste with sea salt and serve with steaks, béarnaise and watercress.