Wash, clean and roughly grate the zucchini. Peel the onion and cut into rings, clean, core and dice the peppers. Mix everything with salt and cover for 4 hours. Express well.
Bring 500 ml of water with sugar and vinegar to the boil, add the zucchini mixture and cook over medium heat for approx. 3-4 minutes. Pour hot into jars and close immediately.
If stored in a cool and dark place, the zucchini can be kept for at least six months.