Cut the Hokkaido pumpkin in half and remove the giblets with a tablespoon. Cook the pumpkin halves in the steamer until soft (I use a pressure cooker with a steamer insert). Puree the pumpkin flesh with the skin using the hand blender. Add the orange juice, sugar, lemon juice and flavor to the pumpkin puree and stir well. Bring the mixture to a boil and cook for 5-6 minutes (remove foam). Add the liqueur. Pour the finished jam into prepared screw-top jars. Let stand on the lid for 5-10 minutes and turn over.