Watermelon jam

1 watermelon with a thick shell
1 tablespoon quicklime

Remove shell from watermelon, leaving some flesh on the shell.
Chop shell in cubes and place them in a big bowl.
Cover with water and add quicklime.

Set aside for 2 hours, stirring gently from time to time.
Drain and weigh.
You will need 750g sugar for every kilogram of shell cubes.

Place sugar in a large saucepan, cover with water and cook over high heat until syrup turns sticky.
Add cubed watermelon shell to the syrup.