Balance the wine with the food

While balance in wine or in food is generally desirable, if a food is acidic (hard) or food is sweet (soft) the wine should match the taste, not counter it. An acidic wine (hard) like a Sauvignon Blanc, would best match the hard taste of a salad with a vinegar-based dressing and thus pair well with it. 

A less acidic wine such as a Chardonnay that has undergone malolactic fermentation (malic acid which is a hard mouth feel is converted to lactic acid which is soft like milk) would match meat with a butter-based sauce (savory)  much better than would an acidic, unoaked Chardonnay.  

I agree– taste is in the mouth.