Cut the cucumber and onions into slices, mix well with the other ingredients in a bowl and let steep for 24 hours. Fill into prepared glasses, close and boil for approx. 3 minutes. Tip: For boiling down I always use a large saucepan in which I put a sponge cloth, put the glasses in and fill up with enough water until the glasses are almost 1/4 in the water. Then carefully bring the water to the boil with the lid closed and cook on the low setting for 3 minutes. Then I put the pot closed on the stove and let the glasses cool down in the pot.