cold roast beef - how can i cook so its delicious, tender and i can serve it for dinner

[celeste28]

in 2 hours please? We had housekeepers cut yesterday and it was really nice but rare. The meat is very chewy today as its cold - i have potatoes and veg etc and was wondering if i could cook the beef so that it tastes the same as yesterday or even like in a casserole for dinner today. when i tried before the beef j ust went really tough and was ruined - many thanks