Put the aubergine chunks in a medium, non-stick frying pan and drizzle with the oil. Season with salt and black pepper and place the pan over a high heat. Stir-fry for 3-5 minutes, or until the aubergine is nicely browned but not cooked through. Tip into a medium bowl and set aside.
Put the minced lamb, onion, garlic, oregano, dried mint and bay leaf in the pan used to fry the aubergine and cook over a medium heat for 5 minutes, stirring and squishing the meat against the side of the pan with a wooden spoon to break up the mince.
Stir in the flour and season with salt and plenty of freshly ground black pepper. Pour over the wine, add the lamb stock, tomatoes and tomato puree. Bring to a simmer and cook for 10 minutes, stirring occasionally. Return the aubergine pieces to the pan and cook for a further 5-10 minutes, or until the lamb is tender, the aubergine is soft and the sauce is thick, stirring occasionally.
Drop the feta chunks on top. Cook for a further 1-2 minutes without stirring, until the feta begins to melt. Scatter over the mint leaves and serve with a large mixed leaf salad.