In a pan over low heat, combine the glucose syrup and sugar, stirring well.

In a mixer, add the egg whites. Ensure the mixer is very clean and dry. Add the vinegar and salt, then whisk until it forms a meringue.

Once the sugar starts to boil, prepare a bowl of cold water. Drop half a teaspoon of the sugar mixture into the water. If it forms a soft ball that can be shaped, it's ready. If it dissolves, it needs more time. Once it forms a shapeable ball, it's ready.

Slowly pour the sugar mixture into the meringue while continuing to beat until well combined.

Then, gradually add the butter piece by piece and the vanilla while beating until you achieve the desired consistency.