Large cuts of beef prepared in the oven are usually referred to as roasts, but to a purist that's just not the case. In a strict sense, only meats cooked by fire are truly roasted. The radiant heat of the coals -- or a gas flame, in a pinch -- gives your beef roast a richly browned crust and hint of smokiness that can't be achieved with oven roasting. Cooking your roast at a fire isn't difficult, though it's a bit more work than a set-and-forget oven.
With a Rotisserie
Season your roast and truss it securely with butcher's twine to help it retain its shape as it cooks. This is optional but very helpful, and also helps most roasts to cook more evenly.
Build a fire of hardwoods or charcoal, and let it die down to a bed of coals. If you're using a charcoal kettle, rake the coals to the side of the kettle where they're parallel to the rotisserie. If your fire is in a firepit or fireplace, rake them away from the area directly beneath the spit. Your goal is to cook in front of the coals, not over them.
Turn the roast in your hands a few times, to get a feel for its balance, then skewer it on the main spit. Use the secondary forks to hold it firmly in place. Rotate the spit a few times, to ensure it's balanced. Some brands include a counterweight you can use to cope with odd-shaped roasts or bone-in roasts such as prime rib, which are otherwise difficult to balance.
Lock the spit into place on the rotisserie, and turn on the motor. Place a pan under your roast to catch the drippings and rendered fat. Use these to baste the roast periodically as it turns, creating a richly savory crust on the outside of the meat.
Adjust the heat as your roast cooks by moving the spit closer or further from the coals. In a charcoal kettle, manipulate the draft instead or use aluminum foil to shield any parts of the roast that are cooking too quickly. Cooking times will vary depending on the cut. It can take as little as 20 minutes per pound to roast a rib eye to medium-rare, while a chuck roast might take several hours to become fork-tender and well done.
Remove your spit from the rotisserie once the meat is done and carry it to a serving tray. Let the roast rest for 10 to 15 minutes before removing the spit, carving and serving.
Without a Rotisserie
Build a fire in a firepit or make your campfire in a ring or angled V-shaped stack of stones. Use charcoal or hardwoods, which lend a pleasant flavor to the meat and burn down to very hot coals.
Place a grate across the fire, keeping it away from the actual bed of coals. Place a pan under the grate to catch drippings from the roast, so the fat doesn't run to the fire and cause flare-ups.
Position the roast on the grate where it receives indirect heat from the coals, but isn't close enough to burn. You might need to place a counterweight such as a stone at the other end, to keep the grate from tipping.
Roast the beef until it reaches your preferred degree of doneness, turning it periodically to ensure even cooking and basting it with the drippings for flavor and a rich crust. Your actual cooking time might vary from as little as 15 to 20 minutes per pound to several hours, depending on the cut, your own preferences and the size of the roast.
Remove the roast from your fire and transfer it to a serving platter. Let it rest under a loose covering of aluminum foil for 10 to 15 minutes before carving and serving.
If you have a wood-burning fireplace in your home, you can use that to cook a roast. Rotisseries are available for fireplace use, or you can simply hang it from a heavy piece of string in front of the coals. It will rotate gently on its own, or you can twirl the string any time you're passing by.
Many gas grills offer rotisserie attachments as well, and can make an excellent roast. Wrap small chips of hardwood in foil and place them near the flame, to replicate the smoke flavor of an open fire, and only light the burners running parallel to -- but not under -- the spit. Some grills have a separate burner specifically for rotisserie cooking, which is an even better option.
The spit and rotisserie become very hot during cooking and give you a serious burn if you handle them carelessly. Always wear heatproof gloves or use towels and tongs to handle the spit and its accessories.