Deep Fried Cod in a Yeast and Beer Batter with Tartar Sauce and Chips Serves 4   - 900g/2lb maris piper potatoes, cut lengthways into chips 1cm/1/2 inch thick - 4 thick pieces cod fillet from the loin end, not the tail, about 175g/6oz each - sunflower oil for deep-frying - salt and freshly ground black pepper For the Yeast and Beer Batter - 15g/1/2 oz fresh yeast or 1 x 7g sachet easy-blend dried yeast - 300 ml/10fl oz beer - 225g/8oz plain flour - 1 teaspoon salt For the Tartar Sauce - 1/2 quantity mustard mayonnaise (see following recipe) - 1 teaspoon finely chopped green olives - 1 teaspoon finely chopped gherkins - 1 teaspoon finely chopped capers - 2 teaspoon snipped fresh chives - 2 teaspoon chopped fresh parsley - fresh parsley sprigs, to garnish Make the batter: if using fresh yeast, in a bowl, cream it to a smooth paste with a little beer, then gradually stir in the rest. Sift the flour and salt into a bowl, make a well in the centre and pour the beer into mixture. Gradually whisk the liquid into the flour to make a smooth batter. Cover and leave at room temperature for 1 hour. If using dried yeast, add to the dry ingredients, then gradually whisk in the beer. Preheat the oven to 150C/300F/Gas2. Line a baking sheet with plenty of kitchen paper; set aside. Combine all the ingredients for the tartar sauce. Set aside. If you don't have a thermostatically controlled chip fryer, use a fairly good-sized pan (about 4.5 litres/8 pint capacity) with a frying basket to fit. Use about 2.25 litres/4 pints oil. (Never overfill a deep-frying pan as it will spill over when the oil boils.) Cooking chips in two stages makes them crisp on the outside and fluffy inside. First blanch them. Heat the oil to 140C/275F and fry the chips in two batches for about 5 minutes, then empty them into a roasting tin. The aim is to cook the potatoes through without colouring them. To fry the fish, heat the oil to 160C/325F, season each piece of fish with salt and pepper and dip them into the batter. Fry two pieces at a time for 7-8 minutes until crisp and a deep, golden brown. Drain on a paper-lined sheet, then transfer onto a metal foil lined tray and keep hot in the oven as you cook the other pieces. Increase the temperature to 190C/375F and fry the chips, again in two batches, until crisp and a deep, golden brown. Serve the fish and chips with the tartar sauce. Garnish with the parsely sprigs. Mustard Mayonnaise (makes about 120ml/4 fl oz) - 1 tablespoon ready-made English mustard - 1 egg - 1 tablespoon white wine vinegar - 3/4 teaspoon salt - freshly ground white pepper - 300 ml/10 fl oz sunflower oil Put the mustard, egg, vinegar, salt and pepper in a food processor or blender. Turn on the machine and gradually add the oil through the hole in the lid until you have a thick emulsion. This recipe contains raw eggs.