Put the lemon zest and juice, sugar and butter into a heatproof bowl. Sit the bowl over a saucepan of gently simmering water, making sure the water is not touching the bottom of the bowl.
Lemon honey (also called curd) made without eggs or butter makes a great gift for vegan friends and although not vegan myself I enjoy it just as much as the egg-based curd. And it is just the ...