How to cook
Mix the melons and peaches in a large pot with a wide bottom, add the sugar and lemon juice and put the jam to boil.
Stir frequently until the sugar dissolves completely. Then continue boiling the jam until thickened while stirring nonstop to prevent burning - its temperature needs to reach 430°F (220 °C).
Usually this takes about half an hour or a bit longer. Stir the prepared jam with the lemon zest.
Pour the jam into 6 sterilized jars through a funnel with a wide opening. Seal them tightly and sterilize the jars for 10 min.
You can store the peach and melon jam up to a year in a cool and dark area. Keep any opened jars in the fridge.