Lightly sprinkle a grill pan with olive oil and pepper and heat to a high temperature. Spread the mustard lightly over the steaks and add the steaks to the pan. Cook for the desired length of time, turning once.
Roquefort and tarragon sauce
Heat the olive oil and butter in a shallow saucepan. Add the spring onions and cook for 1 minute. Now add the wine and boil rapidly for 1 minute – the mixture should start to reduce. Turn down the heat and add the cream, pepper and cheese, stirring occasionally. Allow the sauce to heat through gently until the cheese shows signs of melting. Add the tarragon and stir well. Finally, taste the sauce and add a little salt if required.
In a separate frying pan, lightly toss the mushrooms and asparagus spears in a little melted butter for approximately 1 minute.
Serve the steaks topped with the lightly sautéed vegetables and pour over the sauce.