Puree the strawberries in the blender, grate the zest of the lemon and squeeze out the juice. Scrape out the vanilla pods, pick up the pods.
Mix the strawberries, vanilla pulp, scraped pods, lemon zest and juice with the sugar in a sufficiently large saucepan.
Bring the mixture to the boil, then simmer for about 5 minutes and finally remove the pods. Pour everything into clean, preheated glasses. Close immediately and turn upside down.