Instructions

  1. In a small sauce pan, over medium heat, dissolve sugar into lemon juice. Add zest.
  2. Lightly beat egg in a small/medium bowl. Whisking constantly, slowly pour lemon/sugar syrup into the egg. Beat for 2 minutes (only 1 if you're using a mixer), then transfer back into the saucepan.
  3. Heat over low heat, stirring constantly, until it just starts to bubble at the edges. Remove from heat and stir in vanilla.
  4. Transfer to a small container and store in the fridge.