In a small bowl, mix together the miso, lemon juice, minced garlic and mirin. Rub the steaks with a tiny bit of oil and some seasoning. 

Rub the steaks with a tiny bit of oil and some salt and pepper to season. Place each steak in the bowl of marinade, and allow to sit for about 5 minutes, ensuring they are fully immersed. 

Heat a fry pan until really hot, and add the steaks to the pan, pouring the remaining marinade into the pan with them. Cook for 2-3 minutes each side, or to personal preference.

Transfer the steaks to a plate, cover loosely with foil, and let them rest for 5 minutes. 

Serve with a side salad of your choice.