You have to balance time and heat when cooking beef by the kilo reach final, or target, temperature. Cooking starts when you take beef out of the refrigerator. Give larger cuts, such as those weighing more than 3 kilos, proportionately more time to warm up before cooking, and those weighing 2 kilos or less, proportionately less time. In addition to modifying active cooking time, you also have to modify your beef's resting time so it can reach the target temperature before serving.
Set out the beef you are going to roast and let it reach room temperature, about 15 to 20 minutes per pound, not exceeding 1 1/2 hours. You can let beef sit at room temperature up to 2 hours, but you don't want to cut it that close; place it in the oven after 1 1/2 hours even if it's still a little chilly.
Season large cuts of beef, such as prime rib, liberally with kosher salt right after you take them out of the refrigerator; season smaller roasts, such as sirloin tri-tip, about 10 to 15 minutes before putting them in the oven.
Heat the oven to 350 degrees Fahrenheit. Place an instant-read meat thermometer in the thickest part of the beef and place the roast on an elevated roasting pan or pan with a roasting rack. Place the beef in the oven.
Roast the beef for 40 minutes per kilo for rare, or an internal temperature between 120 and 125 F. Roast the beef for 50 minutes per kilo for medium-rare, or a temperature between 125 and 130 F. Roast the beef for 60 minutes per kilo for medium, or between 130 and 135 F. Roast the beef for 1 hour and 10 minutes per kilo for medium-well, or an internal temperature of 135 and 145 F.
Take the beef out of the oven and transfer it to a carving board or other work surface. Rest the beef for 5 to 10 minutes per kilo; 5 minutes for 1 1/2 kilos or less, and 10 minutes for anything over 2 kilos.
Take the beef out of the fridge about 15 to 20 minutes before starting. Pan-frying is only suitable for smaller cuts of beef, such as 1/2- to 1-kilo steaks and small roasts, so 15 minutes should suffice for most cuts. But, if the beef feels still feels cold after 15 to 20 minutes, you can let it sit out longer.
Heat a few tablespoons of fat in a heavy-bottomed skillet. You can use any fat as long as it has a high smoking point. Animal fats, such as bacon or duck fat, and vegetable fats, such as sunflower or peanut oil, both work; you have a lot of fats to choose from, so it really comes down to taste preference when you pan-fry.
Heat the fat over medium heat on the stove for at least 3 or 4 minutes. Medium heat produces a surface temperature of about 350 to 400 F, which works for thick or thin cuts of beef.
Fry beef that's 1 kilo or less or under 1 inch thick for 5 to 6 minutes total -- 2 1/2 to 3 minutes each side -- for rare, 7 or 8 minutes total for medium-rare and 8 to 9 minutes total for medium.
Fry beef that weighs over 1 kilo, or measures more than 1 inch thick, 8 to 9 minutes total for rare, 10 to 11 minutes total for medium-rare and 12 to 14 minutes total for medium. Turn the beef over only once during cooking.
Take the beef out of the pan and let it rest for 5 to 10 minutes per kilo.
Take the beef out of the fridge about 15 to 20 minutes per kilo before firing up the grill. Grilling works best with very to moderately tender cuts ranging from 1/2 to 3 kilos, so 15 to 20 minutes works.
Set the grill up to cook at a medium-high temperature, around 375 to 450 F. One layer of lump charcoal in the charcoal tray generates medium-high heat in a barbecue. Gas grills only require you set the burners to medium-high. Let the grill heat for about 15 minutes and place the beef on the cooking grate.
Grill beef weighing 1 kilo or less, or cuts under 1 inch thick, for 4 to 6 minutes total -- 2 to 3 minutes each side -- for rare, 6 to 8 minutes total for medium-rare and 8 to 10 minutes total for medium. Use the lower cooking times for thin cuts, and the higher times for thicker cuts.
Grill beef weighing over 1 kilo, or measuring more than 1 inch thick, 8 to 10 minutes total for rare, 10 to 12 minutes total for medium-rare and 12 to 15 minutes total for medium. Turn the beef over 3 or 4 times during grilling; grills distribute heat unevenly, so frequent turning is your friend.
Take the beef off the grill and rest it for 5 to 10 minutes per kilo.