Preparing beef stroganoff requires several steps, but none of them are difficult, even for novice cooks. It requires a moderately tender cut of beef, such as top sirloin, trimmed of all fat and connective tissue. The beef must be sliced thinly into strips, then browned quickly in small batches in a hot skillet. Then, mushrooms and onions or shallots are cooked in the same skillet until tender and lightly browned. Add beef broth to the pan and stir it to get up all the flavorful browned-on juices, then simmer the mixture until it reduces and begins to thicken. Add heavy cream to the mixture and then return the beef to the pan and let it simmer, as it heats through.

Ordinarily, you'd finish the sauce at that point with sour cream and chopped fresh dill. But sour cream isn't heat-stable and it's difficult to successfully reheat your sauce once it's added. Instead, remove the meat and sauce from your stove and pour it into one or more wide, flat, shallow containers. Let it cool, stirring occasionally, for up to two hours or until it reaches room temperature. Cover the containers and refrigerate them or freeze them for later use.

If you've frozen the beef and sauce, move it to your refrigerator a day ahead of time to thaw. That's the safest method and your food remains at a food safe temperature throughout the process. If you're heating and serving it right away, you can also thaw the stroganoff mixture in your microwave oven. Transfer the thawed beef to a saucepan, adding a small amount of beef broth if it's too thick. Reheat the beef gently until it reaches the U.S. Department of Agriculture's recommended temperature for leftovers of 160 degrees Fahrenheit.

While the beef is reheating, bring a large pot of water to the boil. Cook enough medium or broad egg noodles to serve everyone, and drain them when they're fully cooked but not yet soft. Toss the noodles with butter, to lubricate them and keep them from sticking. Spoon some of the sauce from your beef into the sour cream to warm it slightly, then stir the mixture back into your simmering sauce. Sprinkle the beef and sauce with chopped fresh dill, and serve it over portions of buttered noodles.