Wash the rhubarb (do not peel it off), finely chop it and weigh 500 g. Wash the strawberries and weigh 200 g. Shake off the cones a little and use the scissors to cut only the flowers (no stems) from the cones. Put everything in a saucepan and mix with the preserving sugar. Let stand for about 1/2 - 1 hour. Bring to the boil while stirring and let it simmer for 4 minutes. Make the gelation test and fill it immediately into hot-rinsed glasses. Turn over and let stand upside down for 5 minutes.