In a small bowl, sprinkle the gelatin over the water and set aside for about 10 minutes.
Puree the strawberries with sweetener, vanilla, lemon zest and lemon juice.
Transfer the puree in a saucepan and heat over medium heat just until hot. Add gelatin and stir until it is melted. Remove from heat and let mixture cool to a room temperature.
Whip the cream till it just begins to hold soft peaks and carefully fold into the strawberry mixture. Pour into serving glasses and chill for 4 hours.