Place bag of potatoes into microwave, as per packet instructions and microwave for 6 to 8 minutes, or until tender. Set aside covered with foil to keep warm. Drizzle with a little oil and season with salt and pepper, to serve.
Meanwhile, brush steaks with 1 tablespoon oil and season with salt and pepper. Heat a large non-stick frying pan over medium heat. Add steaks and cook for 3 to 4 minutes each side or until cooked to your liking. Transfer to a plate and cover with foil.
Increase temperature to medium-high. Add onion and mushrooms and cook for 4 to 5 minutes or until golden. Add worcestershire sauce, sour cream and 1/3 cup water. Bring to the boil and remove from the heat. Season with salt and pepper. Serve steaks topped with mushroom sauce, baby potatoes sprinkled with parsley, and baby rocket on the side.
You can prep the onions and parsley while the steaks are cooking - potatoes are cooking in the background