Scald peaches with boiling water, rinse and peel the skin. Cut peaches in half and stone them. Dice the flesh. Cut melon into quarters, remove seeds and peel. Dice the flesh. Weigh 900 g peaches and 500 g melon. Wash mint and dab dry. Peel the leaves and cut them into fine strips
Mix melon and peach cubes with jam sugar in a large pot. Bring everything to the boil while stirring over high heat. Then boil for at least 3 minutes while stirring continuously until bubbly
Stir in citric acid and mint. Immediately pour jam into prepared twist-off jars. Seal and let cool upside down