It happens to the best of us, but there's an easy backup solution: dried lemon peel, which is commonly found in the spice section and can last up to two years in the cupboard. Swapping dried lemon ...
Set aside the remaining lemon. Place the peel in a saucepan, cover with boiling water and half the caster sugar and boil for one minute. Drain and pat dry, then put onto non-stick parchment paper.