Put the bulghur wheat in a large bowl, pour over the stock and stir well. Cover with a pan lid or baking sheet and leave to soak for 20-25 minutes or until tender and most of the stock has been absorbed.
While the bulghur wheat is soaking, preheat the grill to medium-hot and line the grill pan with foil. Arrange the vegetables on the grill rack and brush with 1 tbsp oil. Grill for 15-20 minutes or until tender and beginning to char, turning over halfway through and brushing the other side with 1 tbsp oil. Check the vegetables regularly and remove them as they are cooked.
Drain the bulghur wheat. Whisk the remaining oil and 1 tsp vinegar in the bowl, then add the chicken, beans and parsley. Return the bulghur wheat to the bowl. Cut the aubergine slices into halves, or quarters if large, and add to the bowl with the courgette and pepper slices. Mix everything together well. Season.
Heat the butter and remaining vinegar in a small pan. Stir in the mint. Spoon the bulghur wheat salad on to plates and drizzle over the mint dressing. Garnish with mint leaves.
For a spicy dressing, stir a finely chopped, seeded red chilli into the melted butter or whisk in 1/4 tsp chilli paste.
The salad can be prepared to the end of step 3 up to 12 hours in advance and kept covered in the fridge. If possible, remove the salad from the fridge about an hour before you need it, then drizzle over the mint butter dressing just before serving.