WW-- The root's *sal 'salt'. Souse is from MFr souser, OFr soucir 'to pickle' from sous, souz 'pickled meat' from OHG sulza 'brine, jelly, jellied or pickled meat' from *sal-d- 'salt'. Salad is ultimately from Late Latin salata feminine past participle of salo 'to salt'. You've also got salary and salami in there, too.

http://www.bartleby.com/61/roots/IE441.html