Having a birthday supper at my house on Friday.

Gonna cook my wife a fillet (not worried about that one) but my best friend wants to buy porterhouse steaks for him and myself.

He gave me the money to buy them and I am going to cook them.

The nearest "butcher shop" is Trollingers (sp?) in Paris.

I don't mind driving there to get the steaks but I would rather not if possible.

The next best option I have is the local supermarket.

What can I do, without a degree from culinary school, to insure the steaks are not tough?

Generally I will marinate overnight with alegro & apple juice.

Then I will set them out several hours before cooking to let them get to room temp before throwing on the grill.

Any tips would be greatly appreciated.