Koji-Rubbed Steaks with Miso Butter and Whisky

Ingredients

• 1 rib-eye steak (about 1 kg)
• 45 gm (¼ cup) koji rice powder (see note)
• 100 ml extra-virgin olive oil
• 600 gm mixed mushrooms (Swiss brown, king brown and enoki)
• 6 spring onions, thinly sliced
• 1 leek, white part only, thinly sliced
• 4 garlic cloves, thinly sliced
• 60 ml (¼ cup) Japanese whisky
• 150 ml beef stock
• 2 400 gm can cannellini beans, drained and rinsed
• 2 tbsp Worcestershire sauce
• ¼ cup coarsely chopped parsley
• 1 tbsp lemon juice
• Miso butter
• 150 gm unsalted butter, softened
• 2 golden shallots, finely chopped
• 2 tbsp white miso paste
• 2 garlic cloves, finely chopped
• ¼ cup finely chopped parsley
• 2 tsp Dijon mustard