Cut the lemons in half lengthwise. Use the tip of a small sharp knife to gently separate the flesh from the pith. Hollow out the lemons with the aid of a melon baller or small spoon. Reserve the flesh of the lemons.
Place the lemon flesh in a fine sieve set over a bowl to catch the juice. Use your hands to squeeze as much juice as you can.
Put the cold water in a small bowl and sprinkle the gelatine over it. Leave it for a few minutes to swell or ‘bloom’.
Combine the lemon juice, sugar and orange juice in a small saucepan and slowly bring to a simmer, stirring until the sugar is dissolved. Add the gelatine and stir again over low heat until dissolved – do not allow it to boil. Take off the heat and stir in the limoncello.
Place the lemon halves in a small muffin tin to stabilise. Carefully pour in the jelly mixture, filling to the top.
Chill in the fridge for 6-8 hours or overnight until set. Carefully cut each lemon in half lengthwise to create wedges. You might want to snip the ends with scissors to make cutting in half easier. Keep in the fridge until you are ready to serve.
And there you have it. A guaranteed crowd pleaser.