Beets are One more vegetable that shouldn't be reheated. Like spinach and celery, They can be large in nitrates, which convert into unsafe nitrites when reheated. Reheating leftover cooked beets could become a dangerous endeavor you want to skip. Leftover Gravy and Pan Drippings (impression credits: flickr) That delectable gravy https://davidc962jmp2.wikijournalist.com/user