When you are dealing with very high end ingredients, it is more important than ever to let the product speak for itself.
At the restaurant, we rarely use Wagyu, but when we do it is fantastically simple: salt, fresh cracked black pepper. Sear and mark it on the grill, and finish in the oven. A little melted butter on it when it comes out, and that's all.
Do be aware that when you are cooking Wagyu (or, if you're very lucky, Kobe), you actually want to take it to at least medium rare, or even a little bit beyond. I know, that's heresy, and it's coming from a person who likes his steak cooked only to the point where a competent veterinarian could actually resuscitate it at the table. The reason is that when meat is as highly marbled as Wagyu (that is to say, when it has such a high distribution of intramuscular fats), you actually need to cook it further than a lean cut in order to melt the fat and extract all the flavour.
Beyond that, I would agree with Treblekicker. Practice on less-expensive steaks first. Learn how to really maximize the essential beefy flavour of a not-great steak; those lessons will make sure that as you move upwards in quality, you will be getting the most bang for your buck.
So for cooking steaks, a few guidelines:
- Medium is overdone. Seriously. Learn to love your steak red, there is a LOT more flavour
- Learn how to check for doneness by touch; cutting into the meat will release juices = losing flavour. To do this, hold up your left hand, palm facing you. Feel the pad at the base of your thumb. That is blue rare. Touch your forefinger to the tip of your thumb. That is rare. Do this sequentially with the rest of your fingers; that will be med-rare, medium, and well done in order. Well, that's North American colours; the French go slightly less for each level of doneness.
- There is conflicting advice on seasoning (salt and pepper) your steak. Thomas Keller maintains that meat should be seasoned 20 minutes before cooking and left to rest. Harold McGee (I think it was him) says that steaks should only be seasoned after they are flipped. I prefer seasoning before grilling, as the salt helps draw out some moisture which therefore assists in the Maillard reaction (browning and accompanying flavour development).
- Always let your steaks rest a few minutes after cooking. This redistributes juices throughout the meat. In practice, this means taking steaks off the grill or out of the pan a bit before they are done, as carryover cooking (residual heat) will continue to cook the meat.
- Only flip steak once. Try to keep an even cooking time on each side so that the inside cooks evenly. There is a caveat to this however! If you are cooking in a pan, frequent flipping (every 30 seconds or so) will create a much more evenly done steak, and bastes the meat in its own juices. This will come at the expense of slightly less browning, but will be significantly more tender. This is also the best technique for cooking hamburgers in a pan or on a flat-top grill.
- Never squish your steak with your tongs. This presses juices out of the meat.
That's all I can think of for now.
I'm not going to comment on whether or not it is safe, because that could be any number of issues other than the brown coloring of the meat. However, the brown in and of itself is not an issue. When meat is exposed to air it turns a brown color. This does not effect the falvor of the meat, but the color turns a lot of people off. Grocery stores will actually throw this meat away, not because it is bad but just because people won't buy it. Terribly wasteful.
From the USDA: Optimum surface color of fresh meat (i.e., cherry-red for beef; dark cherry-red for lamb; grayish-pink for pork; and pale pink for veal) is highly unstable and short-lived. When meat is fresh and protected from contact with air (such as in vacuum packages), it has the purple-red color that comes from myoglobin, one of the two key pigments responsible for the color of meat. When exposed to air, myoglobin forms the pigment, oxymyoglobin, which gives meat a pleasingly cherry-red color. The use of a plastic wrap that allows oxygen to pass through it helps ensure that the cut meats will retain this bright red color. However, exposure to store lighting as well as the continued contact of myoglobin and oxymyoglobin with oxygen leads to the formation of metmyoglobin, a pigment that turns meat brownish-red. This color change alone does not mean the product is spoiled
Best Answer
A roast should be fine for 3-4 days, refrigerated see:
Beef board reference
If any of several modern packaging systems are used--most of which are designed to exclude air and pathogens, you can get significantly longer storage, although freezing is probably still not a bad idea:
Beefresearch.org