Add the raspberries, sugar, and lemon juice to a blender or food processor.
Blend until the mixture becomes smooth.
Strain the raspberry puree through a fine-mesh sieve to remove the seeds.
Sprinkle the gelatin over the cold water in a small bowl and let it sit for about 5 minutes.
Warm the raspberry puree gently in a saucepan over low heat.
Add the bloomed gelatin and stir until completely dissolved.
Remove from the heat and allow the raspberry mixture to cool to room temperature.
In a large mixing bowl, whip the heavy cream with vanilla extract and a pinch of salt until soft peaks form.
Gently fold the cooled raspberry mixture into the whipped cream.
Continue folding until the mixture is smooth and evenly combined.
Divide the mousse between six dessert glasses or serving cups.
Cover and refrigerate for at least 2 hours, or until completely set.
Garnish with fresh raspberries, whipped cream, chocolate shavings, or mint leaves.
Serve chilled and enjoy.