How can I remove the "over-salted" problem in a cooked pork roast.  I adjusted the sauce with red wine vinegar and brown sugar,which helped, and cut off the outside edges of roast.

I have heard that adding a peeled potato to soup that is overly salty will reduce the salt.  Is this true?

--Susan

There are only a few ways to deal with over-salted food.  One is to throw all or part of it out, as you did with the outer part of the roast.  Another is to mask it, as you did with the wine and sugar you added to the sauce.  And the last way is to dilute it, as you did by adding more liquid (the wine) to your sauce.

Robert Wolke, in his book What Einstein Told His Cook: Kitchen Science Explained, describes an experiment he did where he prepared differing concentrations of salt water, boiled them with potato slices, and then measured for changes in the ability of the water to conduct electricity.  Pure water is a poor conductor of electricity.  If you add salt its conductivity increases, and if you remove salt its conductivity decreases so measuring conductivity is a good way to measure saltiness.  Since he was using only water, salt and potatoes, there were no other ingredients that could affect the conductivity.  The containers were also covered to minimize any evaporation.

What Wolke actually found was a slight increase in conductivity which he attributed to potassium that leeched from the potato slices.  After correcting for that, there was no significant change in conductivity, meaning that adding potatoes to salted water did nothing to decrease the saltiness.

Wolke's conclusion is that, "The potato trick just doesn't work."  The same is likely true for floating a slice of bread on over-salted soup, or using any other ingredient that is supposed to leech salt out of a liquid.

One other possible remedy that Wolke checked out was the idea that one flavor may be able to suppress our perception of another.  He points to a paper that says that salts and acids may suppress each other at high enough concentrations.  The evidence appears to be mixed, however, and the concentrations needed may affect the taste in other ways.

Assuming that you  only seasoned the meat, and didn't brine it, there is evidence that seasoning only penetrates the first 1/16 inch (1.5mm) or so.  You probably did the best you could to resurrect the dish by removing the outer portion and diluting the sauce.  Because brining penetrates deeper, simply cutting off the outer portion may not be adequate.