It's worth a try. Sugar, used in the right proportion, can help cut the edge off other flavors. You might think it's obvious to add sugar to lemon juice to make a less-sour lemonade. By the same token, sugar added to coffee makes it less bitter. And yes, a little sugar (not too much!) stirred into your soup will make it seem less salty.

This approach can be tricky, though. You're not actually covering flavors, you're adding more flavors to distract your tongue from the one you want to be less prominent. Getting the right flavor balance depends on the ingredients and their proportions in your soup. If the proportion of salt to sugar is too small, they'll actually enhance each other. So you want to add enough sugar to cut the salt, but not so much that it makes the soup sweet. You might want to practice this one before putting it to use.

The reverse of this is also true: Bitter, sour, and salty tastes can lower the intensity of sugar. Keep this relationship in mind when checking the labels on processed foods: Sugar and salt are often used to cover less-pleasant flavors that arise when food is processed. Processed foods often contain much more sugar and salt than your palate can detect, and often more than is necessary to balance flavors.

There's another approach that might also be effective. Try the other answers to see what it is, or move on to the next question.