Wash, clean and chop the strawberries. Mix with jam sugar and lemon juice. Chop the marshmallows finely, bring to the boil with cream while stirring and simmer over a low heat until the marshmallows have melted.
Cut the vanilla pod lengthwise and scrape out the pulp. Add the vanilla pulp and pod to the strawberries, bring everything to the boil and let it boil for about 4 minutes while stirring continuously. Remove from the stove.
Fill jam into sterilized twist-off jars with the aid of a jam funnel approx. 2/3 high. Add the very hot marshmallow cream and stir with a spoon handle. Turn glasses upside down for about 5 minutes, turn them over again and let them cool down.