just swap the second teaspoon of lemon juice for Dijon mustard – the extra lemon pairs best with fish. If you want to make this dish for four, use 3 egg yolks and 125g/4½oz butter in the ...

(You can rub the butter in by hand, if you don't have a food processor.) Lightly beat the egg and golden syrup together, add to the food processor and pulse until the mixture clumps together.