1. Buy the cheapest vinegar you can find
2. Pour some vinegar in your kettle, make sure it covers the bottom
3. Top up with water, until the minimum mark
4. Heat the mixture
5. Most of the salt should be gone by now
6. Shake lightly, just so that the mixture has a chance to clean the walls of the kettle
7. If the kettle is not clean by now, you have used too little vinegar, REPEAT with more vinegar (aim for approx 300ml)
8. Your kettle should be clean as new now :)
9. Pour out the mixture, fill it with water and warm it once more, just to remove the smell!
10. Please comment with your results!