I've made this for Christmas dinner for the past several years. It's a nice departure from turkey or ham, and though it takes a few steps, it's not that hard to do. The key is timing, and the potatoes and pudding can start being prepared while the meat is cooking. These sides are so inexpensive that you can afford to pay a little extra for the roast. Serve with horseradish sauce. Add a green veggie or salad, make a nice dessert ahead and you're all set.
I promise to add real pictures of the process after Christmas.
The day or morning ahead: Mix mustards, sugar, and garlic. Spread mixture over the top of the roast. Cover with plastic and refrigerate overnight. (You can peel and cut your potatoes ahead and leave in a bowl of salted water.)
Heat oven to 450°. Set the roast in a heavy, shallow roasting pan, rib-side down. With small sharp knife, score the top fat and sprinkle with salt and pepper. Roast for 15 mins. Reduce heat to 325°. Roast approx 1½ to 2 hours, basting every 15 mins, or until it reaches 135° for medium rare. Move roast to the cutting board. Cover with foil and set aside. Roast will continue to cook to temp. Rest it for 15 minutes before carving.
Pour all but 2 T of the fat and juices from the roasting pan into a bowl. (If your roast was too dry to give enough drippings, just add bacon grease, butter or oil to the drippings to equal 2T+ 1/2 cup + 3/4 cup. Set 1/2 cup and 3/4 cup drippings aside for the potatoes and pudding.
Pudding: In a large bowl, combine flour, salt, and pepper. Mix 1 cup of milk with the eggs in separate bowl, then add it to the flour. Whisk flour and egg mixture until a thick, smooth batter forms. Stir in another 1½ cups of milk. Cover with plastic wrap. Let stand for half an hour.
Place potatoes, a little salt and water to cover into a large pot. Heat oven to 400°. Bring water to a boil, and cook for 8 minutes. Drain.
Place cooked potatoes in casserole in a single layer. Drizzle with 1/2 cup drippings. Roast in the oven until crispy and golden brown, about 30-45 mins.
Heat oven to 400°. If you're going to cook the Yorkshire puddings with the potatoes, your oven should already be at temp.
Continue with the pudding: Gradually stir some of the remaining 1 cup milk into the waiting batter until it becomes the thickness of heavy cream.
Evenly distribute the 3/4 cup drippings between the cups of a 12-muffin tin or two 6-muffin tins .
Place muffin tins with drippings into oven for 5 mins. Take them out when they get very hot.
Pour batter into the muffin tins to 1/3 full. The batter will sizzle in the hot drippings. Return to oven and bake until raised and browned, about 25 to 30 minutes. Serve hot.
GRAVY: Start this once your puddings are in the oven. Heat roasting pan (with the 2 T of drippings in it) on stove over medium heat until hot, then add flour. Use whisk to blend and scrape brown bits & flour from pan until flour is golden. Add stock and wine. Bring to a boil; whisk on med heat until thickened. Season to taste. Set aside - keep warm until ready to serve.