Leave the rib eye to come to room temperature.
Season with salt and pepper and drizzle with olive oil.
Heat a nonstick pan over a high heat.
When the pan is hot, place the rib eye in the middle of the pan and cook for about 7 minutes, then turn the steak and cook for a further 5 minutes, or until the desired doneness is reached.
Place the steak on a plate and cover with foil and leave to rest.
Meanwhile, place a tablespoon of oil in the pan and add the mushrooms and season with salt and pepper.
Add the rosemary sprigs.
When the mushrooms are golden and have released their juices, add the kale and cover with a lid only until the kale is wilted.
Add the cannellini beans and warm through.
Place the steak back into the pan and serve at the table.