Trim the excess fat off the entrecote or rump steak, and render this down in the oven in a fireproof dish with the lid on, adding sliced and peeled carrots, onions, and, if possible, chopped mushrooms, a finely chopped clove of garlic, some salt and pepper.
When the vegetables are soft and have lost their natural moisture take them out.
Either grill the rump steak or fry it in a pan in butter, but only half-cooking it.
Then smother both sides with the cooked vegetables and wrap up the whole thing in a large piece of greaseproof paper, fastening up the edges so that it is more or less airtight and the vegetables don't ooze out.
Put this parcel in a greased fireproof dish and cook in a very moderate oven for 20 to 25 minutes.
Note: The paper, full of a delicious odour of steak, onions, garlic and mushrooms, is undone at the table.