Can I fix a chewy beef joint after it's already cooked and sliced? Now I have cooked the beef joint &amp; it's cut up into thin slices is there anything I can do to make it less chewy.

Editor's note: let's assume this is some kind of cut meant for roasting, presumably something with a fair amount of connective tissue.
Stack the slices up neatly, tie them together with some string and either use a slow-cooker (crockpot), or steamer to finish the cooking

Cook for at least the amount of time it missed on plus about 5 to 10 minutes for it to get back up to cooking temperature

The other option is to cut it up and add use it to make a new stew or casserole