Place flour, sugar, baking powder and salt in a large bowl. Whisk to combine. Set aside.
Crack the egg into another bowl and whisk lightly.
Add milk and whisk again until combined.
Add this to the flour mixture. Add melted butter and lemon juice.
Whisk again to form lump-free, smooth batter. Set aside for 10 minutes. Fold in chopped apples gently.
Heat oil (170C or 350F) in a large saucepan over medium heat.
Once the oil is hot, drop spoonfuls of batter into the hot oil.
Fry until golden on both sides, about 4-5 minutes depending on the size.
Do not overcrowd the pan.
Remove from hot oil using a slotted spoon and drain on paper towels.
Toss in cinnamon sugar, powdered sugar or favorite glaze if you like.