To cook the aubergine, heat oven to 220°C. Paint aubergine with oil and place on a baking tray. Char cook in the oven until the skin is crispy and black, remove from the oven and wrap in aluminium foil, set to one side. The aubergine will continue to cook in the aluminium foil. Note: you can also char grill the aubergine on a gas burner flame and then wrap in aluminium foil.
For the lamb set the oven to 90°C (not fan forced).
Remove almost all of the fat from the lamb and season with salt and pepper.
Heat one tablespoon of grapeseed oil in a frying pan on a medium high heat (setting 8 on Electrolux induction cooktop), add two cloves of garlic and a sprig of rosemary to the pan, place lamb racks in the pan and gently allow them to cook until golden brown all over. Remember to move your racks occasionally to make sure they are not sticking. When all sides of the lamb are done, remove from pan and sprinkle with sansho powder (optional), then place the racks on a bed of rosemary in a baking tray, place in oven on 90°C for one hour.
While the lamb is cooking, you can get started on the sauce. In a large pan bring chicken stock to the boil, then reduce to a simmer (setting 3 on the Electrolux induction cooktop) and add the miso paste. Stir until completely dissolved. Add the blue cheese and continue to stir until dissolved and sauce starts to thicken. Add soy sauce, mirin and ginger, stirring constantly. Remove from the heat and strain the sauce through a fine-meshed sieve.
It is important to taste the sauce as you go, as all blue cheese, soy and miso paste is different and the salt levels will differ.
Once the lamb is cooked, remove from the oven. Remove the meat from each rack in one piece by slicing lengthwise along the bone. Discard the bones and cut the lamb into thick medallions and season with salt and pepper.
Blanch the spinach leaves in boiling water, then plunge into ice cold water to stop the cooking process. Set aside.
Remove the aubergine from the aluminium foil, peel, and slice into quarters lengthwise. Set aside.
To serve, arrange the spinach leaves in the centre of serving plates. Top with the aubergine, then the lamb medallions. Spoon over the miso sauce.
Garnish with spring onions and chives, and sprinkle with black sesame seeds.