You may not want to take the time but I cut out that big thick vein of fat and stuff it with the finely chopped, seasoned and sautéed mushrooms and shallot mix.
Keep the meat flap attached to the meat so you can reassemble the now stuffed piece and tie together with string. Use discrete seasoning on the well oiled (and buttered) piece of meat after you sear the outside. When it has finished resting, it can fall apart a bit when you're carving but your guests can get the perfect bits and serve yourself the crumbly bits.
Just serve one thick piece of meat rather than try to cut two pieces thinly.
Otherwise roast as per following instructions. Buy a good beef stock rather than make your own and serve with sauteed mushrooms.
You know how to roast potatoes and pumpkin. Crisp some prosciutto under the grill or quickly pan fry. When done, dry and crumble the cooked prosciutto and sprinkle over those veges before serving.
Splash a little bit of the red wine you are serving into the sauce which will also help the food and wine matching.