Although the watermelon rind is often thrown away, the white outer wall of the fruit is actually a useful culinary ingredient. This recipe from the 'Food52' blog demonstrates how discarded watermelon skins can be used to make delicious jam.
Instead of throwing away your leftover watermelon rinds, simply peel off the tough green layer of skin and then chop up the white remnants. These bits of watermelon rind can be mixed with sugar and lime and then cooked the same way you would with any other fruit. The skin of the watermelon is particularly useful for jam because it holds its own. The formerly crunchy rind easily turns into a sticky caramelized strew with just a bit of heat. The overall taste is similar to marmalade, meaning it is fragrant with just a hint of a bitterness.
This recipe provides a perfect way to use leftover food scraps and reduce the amount of food that you are throwing out.