Blend the strawberries in a blender to a fine purée. Keep a few for decoration of the glasses.
Add the lemon juice and sugar to the strawberry puree
Pour the purée into the bottom of the carafe, then slowly top up with the prosecco. As it mixes, your cocktail will take on a beautiful pinkish-red color.
Decorate the glasses with the remaining strawberries, pour and enjoy!