Now we proceed to a very important part – the preparation of protein glaze for decorating gingerbread. Put the protein (I had it weighed 35 g) in a bowl, add powdered sugar. First, just mix, and then whisk at the lowest speed for a few minutes, until thickened. Add lemon juice (it will thicken the glaze) and whisk for a couple more minutes. Transfer to a deep bowl. The thickness of the glaze should look something like this: