To make the spiced yoghurt, place the yoghurt in a bowl and stir in the chillies, mint, chives, coriander, parsley, garlic and cumin. Season to taste and cover with clingfilm. Chill for at least 1 hour or up to 24 hours to allow the flavours to develop.
To make the beef koftas, soak the bulgar wheat in a bowl of cold water for 30 minutes. In a separate dish soak twelve 6 inch bamboo skewers in plenty of water to prevent them from burning.
Preheat a grill and line the grill rack with foil. Alternatively, if using a charcoal barbecue, light it 30 minutes before you want to start cooking. If using a gas barbecue, light it 10 minutes beforehand.
Heat a frying pan with half of the olive oil and gently fry the chilli, onion, ground coriander and cumin for 15 minutes until well softened but not coloured. Remove from the heat and leave to cool, then tip into a food processor.
Add the beef to the onion mixture in the food processor with the egg and half a teaspoon of salt and blend to a smooth paste. Transfer to a large bowl. Drain the bulgar wheat in a sieve, then squeeze dry and, using your hands, work into the beef mixture with the pine nuts, mint and parsley. Season to taste. Using wet hands, shape small handfuls of the mixture into log-shaped koftas. Repeat with the remaining mixture until you have 12 koftas in total.
Brush the grill rack of the grill or barbecue with the remaining oil and cook the koftas for 8-10 minutes until cooked through and browned. Drain on kitchen paper and then divide between warmed plates with some salad, if liked. Serve with a bowl of the spiced yoghurt for guests to help themselves and salad, if desired.