After 40 minutes, the protein powder will almost completely dissolve in water, now you can cook meringue. Start whipping at a low speed of the mixer, after 3-4 minutes gradually increase the power and whisk until a homogeneous foam appears. We start adding sugar gradually, in small portions. When all the sugar is added, without stopping whipping, add powdered sugar in two steps. Whisk to medium peaks (the top is slightly tilted). At the end of whipping, add starch, lemon juice and vanilla, mix lightly with a mixer at low speed.