For deep-frying: vegetable oil3sebago potatoes (about 1kg), cut into thin chips, rinsed under cold water, dried well4pieces onglet steak (200gm each; see note), at room temperatureCafé de Paris butter125 gm softened butter1½ tbsp each finely chopped chives, tarragon and parsley2golden shallots, finely chopped1garlic clove, crushed1 tbsp capers in vinegar, finely chopped3anchovy fillets, finely chopped2 tsp Worcestershire sauce2 tsplemon juice½ tsp Indian curry powder, such as korma½ tsp sweet paprika
Preheat oven to 200C. Preheat oil in a saucepan to 140C. Deep-fry chips in batches until just cooked (3-5 minutes; be careful as hot oil will spit), drain well, pat dry with absorbent paper. Transfer to an oven tray lined with baking paper and bake until dry (15 minutes).
Meanwhile, heat a large ovenproof frying pan over high heat, add steaks and cook, turning occasionally, until cooked rare (2-4 minutes each side). Transfer to oven and cook until medium-rare (3-5 minutes).
For Café de Paris butter, beat ingredients in a bowl to combine, season to taste, set aside.
Increase oil to 180C. Deep-fry chips until golden and crisp (5-10 minutes; be careful as hot oil will spit). Drain on absorbent paper, season to taste and serve with steak topped with Café de Paris butter.