Mix together the strawberries and sugar. Allow to sit for a few minutes until the sugar begins to pull the moisture out of the strawberries.
Cook over a medium heat until boiling, and then simmer until the mixture is very thick. You should be able to drag a line through the mixture with a spatula, and see the bottom of the pot.
Remove from the heat, stir in the lemon juice, and allow to cool to room temp. Put in the fridge to cool completely.
In a large bowl, whip the cream, vanilla, and condensed milk to soft peaks.
In a freezer safe container, add half of the whipped cream. Spoon over half of the strawberry mixture, and drag through a knife to ripple.
Top with the remaining cream, and repeat with the strawberry. Place cling film directly on the surface, and freeze until completely firm.
To serve, remove from the freezer and allow to sit for a couple minutes until soft enough to scoop.