Fresh berries must be washed and cleared of twigs and seeds, placed on a dry surface and dried well.
Place the berries in a blender bowl and puree. Rub the resulting mass through a fine sieve until it becomes homogeneous.
Place the remaining puree into a saucepan, add sugar, add water and bring to a boil over medium heat. Boil the mixture for 2 minutes. Refrigerate.
Strain the cooled berry compote through a sieve into a saucepan, add berry puree there. Over medium heat, pour the semolina into the mixture in a thin stream, stirring constantly to prevent lumps from forming.
Cook the mixture until thickened, this will take about 3-5 minutes. Cool, the mixture should be medium thick. Blend the cooled berry mass with a blender at maximum speed. The longer you beat, the fluffier and airier the mousse will be.
Place the whipped mousse in bowls and refrigerate for several hours, preferably overnight.
When serving, garnish the mousse with slices of fresh berries.