How should beef be thawed?

Beef may be thawed in one of three ways: in the refrigerator, in cold water, or in the microwave. Never defrost whole-muscle beef at room temperature. Surface areas will thaw at a quicker rate than interior areas, leaving them vulnerable to bacterial growth once they reach a temperature of 40°F. That may be well before the interior thaws. 

• Refrigerator: Steaks may defrost within a day, though bone-in parts and whole roasts mayrequire 2  days or longer. Once the raw beef defrosts, it can remain in the refrigerator for 3-5 days, assuming it was frozen immediately upon purchase. If you decide not to use the beef, you can safely refreeze it within the same time period if it has remained refrigerated at a temperature of 40°F or lower.

• Cold water: Do not remove packaging when defrosting meat in cold water. Be sure the package is airtight or put it into a leak-proof bag. Fully submerge the beef and change the water every 30 minutes, so that it remains cold. Small packages of beef may defrost in an hour or less; a 3- 4 pound roast may take 2-3 hours.

• Microwave: Plan to cook the meat immediately after defrosting, as some areas may become warm and begin cooking during microwaving. Holding partially-cooked food isn't recommended because any bacteria present may still be active. 

Never refreeze beef that has thawed to a temperature greater than 40°F. Freezing will inactivate but not kill any bacteria that may have accumulated as a result of thawing beef to a temperature of 40°F or greater. Once beef reaches a temperature greater than 40°F, it should be cooked immediately.
 
Source(s):
USDA Fact Sheet "Beef...From Farm to Table"