Combine the marinade ingredients together and add the steaks. Leave to marinade for at least 6 hours and ideally 2 days.
As Roccbox is coming up to temperature, remove the steaks from the marinade and leave to come up to room temperature whilst you make the gremolata – combining all the ingredients together and setting to one side.
Ensure all the other ingredients (bacon lardons, diced onion, garlic clove, cannellini beans and chicken stock) are all prepared before heating a grill pan in Roccbox until smoking hot.
Season the steaks well and add to the hot grill pan. For medium rare, cook for around 3 minutes on one side before turning over, adding a knob of butter, some garlic and dry herbs and cooking for a further 1 1/2 minutes.
Remove the steak from the pan and place onto a resting rack or plate, leaving to rest whilst you make the garnish.
Pop a clean pan into Roccbox with a lug of olive oil, add the bacon in and cook until beginning to crisp – around 4 minutes. Add the red onion and garlic and cook for a further minute or so to soften before adding the drained beans and the stock and checking the seasoning. Cook for another 2 minutes in Roccbox, stirring often and checking the seasoning again.
Remove from the heat and turn off Roccbox. Pop the steaks back in Roccbox for 1 minute to warm up.
Mix the gremolata through the beans and put on serving plates, topping with the hot steaks.