Marcella Hazan, or at least her cook book, The Essentials of Italian Cooking, first introduced me to this recipe. It is so very easy, but make sure you are spending some time at home. It does take about 3 hours to cook.
Roast Beef with Onions
1 large onion, peeled, halved, and cut into thin slivers
2-3 pounds beef (such as a rump roast), if the roast is very tall, I usually cut it in half
salt and pepper to taste
Place slivered onions in the bottom of an enameled cast iron pot (I use Le Creuset). Place beef on top of onions. Sprinkle with salt and pepper. Cover pot and put in the oven. Turn oven to 325 degrees. Let beef cook for about 3 hours. Remove from oven. To serve, pull beef apart and place on plate. Top with onions and juice. I serve with green beans and shallots and mashed potatoes.
If you have leftover beef, make beef and onion soup the next evening.