For the chutney: Mix the mango puree and the coconut milk together. Fold in the cilantro, mint, garam masala, salt and turmeric
For the onions: In a frying pan, saute the onions until three-quarters cooked. Add the balsamic vinegar and salt, and reduce until the onions are fully caramelized.
For the kebabs: Preheat the grill. In a large bowl, add the lamb, garam masala, sugar, garlic, ginger, chile flakes, cilantro, egg and some salt, and mix well. Portion and roll into balls of desired size.
Grill the kebabs until cooked through, turning occasionally to ensure even cooking.
To serve, warm the naan, then spread some chutney on each piece. Next, place some balsamic onions, followed by a few grilled kebabs. Wrap up and serve immediately.