"Never" you say! White wine with fish and red wine with beef is the convention. Let's turn the table!
Recently, I wrote a blog on how well a good Pinot Noir goes with a dense gamy fish life swordfish. This is a perfect example of a red wine matching well with fish. Another great example is matching a big, buttery Chardonnay with beef stroganoff. For a great recipe for beef stroganoff, see DAZ in the Kitchen, a wonderful blog on food written by my wife, Deanna Lang.
My wife's beef stroganoff is very rich and creamy. The mushrooms are cooked in butter and the gravy is very rich. The richness and creaminess of the gravy, mushrooms and fettuccine noodles almost demand a similar style white wine like a big, buttery Chardonnay. There are several choices for this including a decent aged Montrachet, an aged big, rich Hunter Valley Chardonnay such as the Alexander Munro Chardonnay from Meerea Park, or the aged Chardonnay from Waverly Estate, or a Chardonnay from Margaret River such as the Leeuwin Estate Art Series or one from Pierro.
The point is "rich and creamy" gravy and "rich and creamy" white wine go very well together. The gravy and noodles contributed more to the overall taste of the meal than the beef (mildly seasoned) did.
Therefore, while it is generally a good and safe rule to match "white wine with fish" and "red wine with beef", you are missing out on a great combination if you are not willing to try to match the more subtle flavors and textures involved. Next time you have a heavy, rich, creamy gravy made from mushrooms cooked in butter, try a big, rich Chardonnay.
BTW, never drink a Montrachet before its time - it is absolutely sinful -
but then again, don't wait too long or you will be pouring good money
down the drain - literally! But then if you are buying Montrachet, I
expect you are careful about this and know what time frame in which to
drink the wine.