Use a waxy potatoes such as pink-eye, sebago or Dutch cream.
6 large potatoes
375ml beer, chilled
250ml sparkling mineral water, chilled
250g plain flour
250g corn flour
1 Tbsp salt
Freshly ground black pepper, to season
Rice bran oil, to deep-fry
Jalapeño tartare sauce
1 1⁄2 cups whole egg mayonnaise
10 cornichons, finely chopped
2 Tbsp baby capers
2 Tbsp finely chopped coriander
2 Tbsp finely chopped at-leaf parsley leaves
2 Tbsp chipotle in adobo sauce, finely chopped
2 Tbsp finely chopped jalapeño chillies
Preheat oven to 180°C fan-forced (200°C conventional). Put whole potatoes on an oven tray and bake for 1 hour or until tender.
Meanwhile, to make Jalapeño tartare sauce, mix all ingredients in a small bowl. Set aside.
Remove potatoes from oven and place on a wire rack to cool. Cut potatoes into 1.5cm-thick slices.
Mix beer and mineral water in a jug or bowl.
Combine plain flour, cornflour and salt in a large bowl. Season with pepper. Make a well in the centre. Gradually add beer mixture, stirring, until batter is smooth.
Pour oil into a large, deep saucepan until 5cm deep. Heat to 190°C on a cook’s thermometer, or until a cube of bread turns golden in 30 seconds.
Working in 3 batches, dip potato slices in batter and drain excess. Deep-fry for 2-3 minutes or until golden and crisp. Drain on paper towel.
Arrange potato cakes on a platter and serve with Jalapeño tartare sauce on the side.