right away. Once you cook the meatballs, you can store them in the refrigerator as you would other leftovers, for 3 to 4 days. Or you could freeze the cooked meatballs, for up to 3 months. While the package of ground beef will be okay until the best before date, once the package of ground beef is opened, it should be cooked or frozen within 1 day. When I purchase onions in 2 lbs or 5 lbs bags where should I keep them?  Thanks! Dear Mrs Cookwell, I am making lasagne from some FROZEN mincemeat. If I have some lasagne leftover, can I put it in the fridge and reheat it the next day? Thank you! Yes, you can refrigerate the leftover lasagne and reheat it the next day. In fact lasagne often tastes better the second day! The key is to ensure that your lasagne has been thoroughly cooked in the first place. Use a food thermometer to make sure the internal temperature has reached 160F (71C). And then, once it is cooked, make sure the leftovers are refrigerated as soon as possible. Don't let the lasagne sit at room temperature for more than two hours. If you divide the lasagne into smaller containers, it will cool much more quickly in the fridge. You can store the leftovers for 3 to 4 days in the fridge or up to 3 months in the freezer. We cooked a precooked ham last Sunday then put it in the fridge. On Friday