How long to cook an 8 lb filet mignon?

The length of time depends on several things, including

• what temperature are you cooking it to (rare, medium, etc)
• what seasonings are you using
• whether you are cooking it whole or as steaks.

To be honest though, I personally have never seen a 15# filet mignon. A filet mignon is actually a very small part of a beef tenderloin. The best filet there is only about 5 filets out of one tenderloin and the rest is used for other pieces.

See Related Links for a cooking chart and tips.