I’ve tenderised chicken in buttermilk for years, so why not steak?
No buttermilk? I used 200ml milk with a tablespoon of lemon juice, which works just the same. Add roughly chopped parsley, sage, rosemary and thyme (yes, I had the song in my head), ½ tsp salt, a teaspoon of Dijon and plenty of pepper. Marinate the rump steaks overnight.
A little aside: I’ve almost stopped using cling film at home. It can’t be recycled, so I use baking paper, or reusable bags I wash and reuse again and again.