Delicately wash the strawberries without removing the stems (otherwise they absorb water and have less flavour). Now remove the stems, cut the strawberries into small pieces and put them in a bowl. Add the sugar and teaspoon of lemon juice; mix well, cover and place in the fridge for at least an hour. Then put the strawberries through a food mill and keep the purée you obtain (which at La Vialla has been christened “La Fragolina”, literally the little strawberry) in the fridge, ready to serve.
Put the chilled strawberry purée into a large jug and, tilting it, pour in the sparkling wine (also well chilled) a little at a time (1). Stir delicately with a long wooden spoon, without agitating too much, otherwise the wine will lose its fizz, and serve immediately in flute glasses decorated with the large strawberries (leave the stems on them, cut a slit in the bottom and slot them onto the glasses).
This exquisite aperitif will earn you many compliments from your friends.
(1) This delicate procedure is required because the wine foams abundantly when it comes into contact with the strawberry purée; so you need to do it calmly and steadily (taking care not to let the aperitif warm up!).