Preheat the oven to 180C/350F/Gas 4.
Soak four wooden skewers in a bowl of cold water for 10-15 minutes, then drain.
For the koftas, place all of the ingredients, except the flour and oil, into a food processor and blend until well combined. With floured hands, shape the meat mixture around the wooden skewers, then rub the oil over the meat.
Heat a griddle pan until smoking and cook the koftas for 3-4 minutes, or until browned on all sides. Transfer to the oven for 6-8 minutes, or until completely cooked through.
For the tzatziki, mix together the yoghurt, garlic and mint in a small bowl and season, to taste, with salt and freshly ground black pepper.
For the caramelised lemon, heat a frying pan until smoking and place the lemon, cut-side down, into the pan. Leave to cook for 4-5 minutes, until the flesh is caramelised and dark brown in colour.
To serve, pile the herb leaves on a serving plate, drizzle over the balsamic vinegar and olive oil and arrange the koftas on top. Serve the tzatziki in a small bowl on the side and garnish the plate with the caramelised lemon.