Put the strawberries, nectar and finesse in a saucepan. Stir the preserving sugar into the fruit mixture. Bring everything to the boil while stirring over high heat and simmer for at least 3 minutes, stirring constantly. Then take it off the hob. Immediately fill the prepared glasses to the brim. Close the lids with the twist off, turn them over and let stand on the lid for about 5 minutes.