How to Cut Corned Beef
Before you cut corned beef, cook it and let it rest under some aluminum foil for 10-15 minutes so it's juicier when you cut it. Then, if you cooked a whole brisket, cut through the fat with a knife to separate the beef into 2 cuts of meat. Next, cut off the thick cap of fat on the side of the meat, and flip the meat over to find the direction the grain runs in. Finally, cut the corned beef into thin slices, cutting against the grain of the meat.
Cook the corned beef before cutting it. Stick a thermometer into the center of the brisket to ensure its internal temperature is around 165 °F (74 °C), hot enough to melt the tough collagen in the meat. Cutting corned beef early causes it to lose its juices, so leave the brisket whole with all the fat on it. At a minimum, cook the beef to 145 °F (63 °C) before cutting it. At that temperature, the beef is safe to eat, although cooking it slowly to a higher temperature makes it taste better. Rest the meat under aluminum foil for 10 to 15 minutes. Move the corned beef to a cutting board as soon as it's done cooking. Cover it loosely in foil to keep it warm while it rests. Waiting allows the meat to reabsorb the moisture inside of it, so you end up with a juicier brisket and a cleaner cutting board. Remove the beef from heat sources, including hot liquids, to prevent it from overcooking. This rest period is the perfect time to finish preparing vegetables or other components you plan on serving with the corned beef. Choose a sharp knife to cut through the beef with ease. If you are able to, get a knife that is as long as the corned beef is wide. That way, you are able to cut the meat into whole slices instead of uneven chunks. A long meat carving knife is the best tool to have, especially for large briskets. Sharpen your knife to ensure it cuts cleanly through the beef instead of tearing it. Use a meat fork to hold the beef in place while you slice it. Slice through the fat to separate the cuts if you cooked a whole brisket. A whole brisket actually consists of 2 parts. A connective layer of fat separates these parts. Gently pull the beef apart with a meat fork to expose the fat in the middle, then slide your knife horizontally between the brisket to separate the cuts. The bigger portion is called the flat. It's leaner and has an even thickness. The fattier part, called the point, is smaller and sits on top of the flat. Flat and point portions are often packaged and sold separately, so you do not need to get a whole brisket to enjoy good corned beef. Trim the fat cap off of the corned beef. Position the beef flat on the cutting board with the puffy, white fat face up. It may be a little browned from cooking, but it's still easy to recognize. Pin the beef in place with a meat fork, then slide the knife underneath the layer of fat. Cut horizontally along the beef to separate it from the fat. Leaving some fat, about 1 in (2.5 cm) or less, is fine. The fat adds flavor. Removing the fat before cooking the beef is possible, but the fat helps seal moisture and flavor in the meat. Flip the beef over and find its grain pattern. Place the fat side down if you left any on the exterior portion of the corned beef. Look closely to see which way the muscle fibers are oriented in the beef. They look like parallel lines along its entire length. Flat and point portions have different grain patterns, so always cut them separately. The grain is not the same as grill marks. If you cooked the beef on a grill, ignore the grill marks and look for the lines formed by the muscle fibers inside the meat. Turn the meat so you are able to cut across the grain. Your knife needs to run perpendicular to the grain, not parallel to it. That way, you shorten the muscle fibers, making the corned beef much more tender. Long muscle fibers are strong and hard to chew. Briskets have long, tough muscle fibers because they come from a weight-bearing part of the cow. Not cutting against the grain potentially ruins good corned beef. Cut from the corner of the leaner end of the meat. The smaller, leaner portion is easier to cut. Hold the corned beef in place with a meat fork, then work your carving knife down into the meat. To cut through cleanly, move your knife back and forth, almost like you're operating a saw. By doing this, you alternate bringing the knife's tip and opposite end in contact with the meat. Push the knife downward as you cut through the meat, gently shaving it into slices. To make a big piece of beef more manageable, cut it in half. As long as you cut it vertically across the grain, reducing its size before slicing it is safe. Slice the rest of the brisket as thinly as possible against the grain. Slice the corned beef about ⁄ 8  in (0.32 cm) thick, if possible. The thinner you are able to slice the beef, the easier it will be to chew. Continue cutting across the grain, slicing the beef into roughly equal portions until you reach its other end. Thicker cuts require more chewing but are still fine to use. Some people even prefer their beef that way. Thicker cuts also serve great in recipes such as corned beef hash. Store leftover beef in the refrigerator for up to 4 days. To keep the beef safe to eat, move it into the refrigerator within 2 hours of cooking it. Place it in resealable plastic bags or containers, labeling them as necessary. Alternatively, wrap the beef tightly in foil or plastic wrap to enjoy the leftovers within the next few days. To freeze beef, put it in a labeled, freezer-safe container. Freezing it will maintain its quality for up to 3 months. Spoiled corned beef looks slimy and has an unpleasant, rotten smell. Throw the beef away without tasting it if you suspect is has gone bad. 
Cook the corned beef before cutting it. Rest the meat under aluminum foil for 10 to 15 minutes. Choose a sharp knife to cut through the beef with ease. Slice through the fat to separate the cuts if you cooked a whole brisket. Trim the fat cap off of the corned beef. Flip the beef over and find its grain pattern. Turn the meat so you are able to cut across the grain. Cut from the corner of the leaner end of the meat. Slice the rest of the brisket as thinly as possible against the grain. Store leftover beef in the refrigerator for up to 4 days. 