Cut the lemons in half lengthways and scoop out the flesh, reserving the hollowed-out halves. Chop the flesh in a blender, then push through a sieve into a bowl. Discard the pulp in the sieve. Measure out 100ml juice (top up with water if you need to), then pour into a pan with 50ml water and the sugar. Bring to a simmer.

Meanwhile, soak the gelatine in cold water. Remove the juice mixture from the heat. Squeeze the excess water from the gelatine, then add to the pan and stir to dissolve. Pour in the vodka and triple sec.

Set the reserved lemon halves, cut-side up, in the holes of a muffin tin and fill to the top with the jelly mix (pour any leftovers into cups). Leave to set in the fridge overnight.

Cut each half into two wedges and serve well chilled.