Mix the flour, nuts and salt in a bowl. Add the beer to the flour in one go, whisk until smooth. Stir in the egg yolk, honey and oil, cover and chill for approx. 30 mins. Shortly before frying, beat the egg white with the salt until stiff, add the honey, beat briefly then fold into the dough.
Peel and core the apples, slice crosswise into rings approx. 1 cm thick. Combine the lemon juice and honey, mix with the apple rings, cover and leave to steep for approx. 30 mins.
In a pan, whisk the milk and all the other ingredients up to and including the egg. Bring to just below the boil over a medium heat, stirring constantly. Remove the pan from the heat, whisk for a further 2 mins., pour into a bowl through a sieve, cover and allow to cool.
Heat the oil to 190°C. Dip the apple rings in the batter in batches, drain and cook for approx. 1 1/2 mins. on each side until golden brown, drain on paper towels. Place the sugar in a dish, dip the fried apples in the sugar and serve warm.