Clean and slice the strawberries. Purée in a blender. Meanwhile, soften the gelatin in a bowl with about 2 cups of cold water. While the gelatin is soaking, heat 1/3 of the puréed strawberries.
Add the gelatin and allow it to melt completely. Add the rest of the purée. Cool the strawberry mixture to room temperature. Meanwhile, whip the cream (which must be very cold). Fold into the cooled purée.
Fill individual molds with the mixture. Chill the mousse in the refrigerator for at least one whole day.