Put 1 1/2 cup of berries, a pinch of salt and sugar in a suitable pan on the stove and allow to boil. Reduce heat and cook until the berries soften. This requires about 5 minutes.
Add lemon zest and lemon juice. Remove from heat, add the remaining berries and allow the cream to cool to room temperature. Beat the vanilla and 1 tablespoon sugar well.
Add the berry mixture gently, saving about 1/3 cup of it. Divide into bowls, pour over the remaining berry mixture and optionally serve with crackers.