This seems like a simple question but I had my surgery on the 3rd and this weekend I'll be starting the puree diet? How does one make puree roast beef?

Can't tell whether you are joking or are serious?  It will depend on your surgery.  If it is an RNY you will need to stay away from beef for at least 1 month.  Many people can handle it from the get go...Others it may take months to digest...Some can never eat it again (hard to digest).  Just follow your surgeon's food guidelines for the first few months.  There is a reason they were put there (like healing from your surgery).  Allow the healing process to take place... 

Till you overcome from health issues stay on the puree diet as health comes in priority.You didn't mentioned which kind of surgery you have undergone but only take natural foods till the time you recover.

Your nutrionist and/or surgeons office should have given you a schedule of what food to start when.

I think perhaps you wanted to know how to make it.  Put cooked roast beef and beef broth in a blender or magic bullet.  Blend until the consistency of apple sauce.  

I was told to stay away from the red meats all together until 6 months out