I recall reading that you should not salt beef until after it is cooked or it will dry the beef. Yet I see recipes that call for salt in a beef marinade. Is it true that you should only salt beef after it is cooked?
Several sources as Cook's Illustrated, Alton Brown, and Anita Lo practically insist that you salt steaks before cooking them. I don't think McGee experiments with or discusses exactly when to season/salt a steak in his books, but he has reportedly stated that he is also in favour of pre-salting. The fact that so many people seem to prefer this technique would seem to indicate that there's at least some merit to it, even if the science isn't well-understood.
All of the arguments I've heard against salting steak (or beef in general) before cooking seem to be anecdotal in nature. When pressed for an explanation, many of these people claim that the salt draws out moisture which will subsequently dry out the cut.
In practice, the amount of moisture it draws out is practically negligible unless you actually cure it, which means using lots of salt and letting it sit that way for a long time. I don't know anybody that does this. Well, hardly anybody (warning: do not follow the advice on that page unless you are fully prepared to ruin a perfectly good steak).
When pressed, most of these people (including Anita Lo, above) say that the water it draws out to the surface will inhibit the Maillard Reaction. This is true - the presence of water does inhibit the Maillard reaction and any significant quantity of water will give you a steamed gray steak instead of a delicious seared brown one. But the key word here is significant. No reasonable amount of seasoning will draw out so much moisture that you actually end up with a puddle of boiling water underneath the steak, and even if it did, you would simply pat the steak dry before searing it. You do pat your steaks dry, don't you?
Also note that this applies to dry seasoning. When marinating a cut of beef it is another story entirely. Salt in a marinade really does create brining and that will tend to make the meat juicier. When meat brines, it absorbs extra moisture - the meat still loses moisture when cooked but the added moisture from the brine helps to offset it (this, again, is all in McGee). A saline solution also dissolves a portion of the tougher proteins in the meat, resulting in a more tender result. Salt is a great thing to have in a marinade, which is why some of the simplest of marinades - soy or teriyaki sauce - are so effective. Just, again, make sure to pat that beef dry before pan-searing it if you want to get any sort of browning going on.
Anecdotally - for what little that's worth - I find that there's very little difference in tenderness whether seasoning with salt briefly before or shortly after cooking (before resting). I've done both and I honestly don't think I could identify which was which in a blind test, except perhaps for the consistency of the "crust" that forms when you really pile on the salt - this is a favourable result for many, and I'll often do this if I'm in the mood.
But all in all, the scientific data on this subject is scant; the results are very inconclusive. And it just doesn't matter that much; the debaters seem to put entirely too much emphasis on this point when there are far more important factors in preparing a great steak or roast, such as additional seasonings, what it's seared in, temperature and heat distribution of the pan, and let's not forget the cut and grade of meat. These things have profound effects on the final result, and if I were obsessive about beef to a fault, then I would concentrate my efforts more on finding better quality ingredients and equipment rather than fussing over the salt issue.
Salting beef is no problem at all. The salt can extract water from the meat, but in a marinade it might act slightly like a brine, taking water out and pulling some of the marinade in.
Even outside of a marinade - pulling water out of the beef simply increases its beefiness (umami) flavor. This is the same principle (although different approach) in dry aging beef. For an extreme version of using salt as a tool to pull water out and increase meat quality, see my answer on Rinse the salt off a steak before cooking? Water is generally steamed out of the meat during cooking anyways so you're probably not losing much in terms of juiciness.
The reason we select prime meats is for its marbling of fat. Reasons for ageing beef are to allow it to dry out (remove water). Water in beef serves no purpose other than extending cooking time and steaming the beef. My objective in preparing an expensive cut of beef is to preserve and enhance the flavor and develop the optimum texture. Water makes that difficult. Beef does not get juicy from water but from that expensive fat marbling we look for. In my opinion any technique that removes water from the beef is worth the effort. Salting hours before cooking and then removing the salt before preparing is the best method I've found.
After getting advice from this site, and experimenting on my own, I've settled on a technique I like for cooking a good steak.
I'll marinade tougher cuts of meat in something acidic for about an hour or less. Then, no matter what cut of meat, I pat it dry and add a little salt. Then it sits for 30 minutes to absorb the salt. I might add a little pepper before I cook it, but usually not.
I cook it in a cast iron skillet. Start off with the skillet CRAZY hot and sear both sides of the steak, then lower the heat (but it should still be pretty hot). Cook until an instant-read thermometer tells me the internal temp is about 135.
Take it off the heat and let it rest for about 20 minutes. During this time the internal temp should continue to rise until it hits about 140 or 145 -- perfect medium rare.