Wash the strawberries, remove them from the stalk and cut the fruit into small pieces. Peel the oranges so that the white skin is no longer visible and fillet them.
Mix the strawberry pieces and orange fillets in a tall saucepan with the preserving sugar, bring to the boil while stirring and let simmer for about 5 minutes. Just before the end of the boil, add the orange liqueur, let it steep and pour the finished jam hot into prepared screw-top jars.