Mix the ingredients in a large bowl using a hand whisk; don't forget to taste the mousse and adjust the amount of sweetener or lemon zest.
Once all the ingredients are combined together, you can arrange the portions into small cups or bowls. The preparation is so quick that you don't even need to make this dessert in advance.
Add a little bit of lemon zest on top before serving (garnish, optional).
Notes
If you want a dessert with just a hint of lemon use only 10 ml of lemon juice.
For a stronger taste of lemon, increase the amount of lemon zest - up to 3/4 tsp.
This recipe has a low amount of sweetener but feel free to taste the mousse and adjust the flavour according to your preferences.