Add pork roast, beer, sherry, garlic, vegetable base, mushrooms, and seasonings to sous vide bag and vacuum seal. You can do this as is with a chamber vacuum, or alternately freeze the liquids in the bag and then seal (if you do this omit the sherry until later). Another method is the immersion method with a gallon ziplock bag (that method can be found on the internet). Cook pork for 8-12 hours at 134 degrees Fahrenheit for a medium temperature. Remove liquid contents from bag and place in sauce pan. Add ¼ to ½ cup heavy cream (and the sherry if not added earlier) and heat through. You may choose at this point to immersion blend a few of the mushrooms for a thicker sauce. Place the roast under a low broiler and broil for about 5 minutes if you desire the top to be browned (we do the fat side). Serve sliced with sauce and mushrooms.