Cut the lamb and chicken into large dice. Peel and de-vein the prawns.
Zest the lemon, peel and roughly chop the garlic, pick the mint leaves and discard the stalks. Blend half the zest, garlic and mint in a food processor with the cinnamon and enough olive oil to make a loose paste. Coat the lamb with this and leave to marinate, overnight if possible.
Finely chop the chillies (leave the pith in if you like it hot!) and the parsley. Toss these with the prawns, along with the remaining lemon zest and a little olive oil.
Peel and finely slice the shallots, and finely chop the coriander - stalks and all. Whisk together the harissa and about a tablespoon of olive oil, then toss this together with the chicken, shallots and coriander. Leave to marinate.
Halve the peppers, remove the stalks, pith and seeds and cut into rough 3cm squares. Remove the stalks from the mushrooms. Top, tail and skin the onions, cut into quarters and pull apart the leaves. Toss all the vegetables in olive oil, salt and pepper, place in a roasting tray and cook in a 200c oven for about 15 minutes. They should soften a little and not take on too much colour - they will finish cooking and browning when they are grilled. Remove and leave to cool.
Get a large chargrill pan or barbecue as hot as you can. Season the meats with salt and pepper. Allow your guests to put together their own kebabs, then grill until the meat is just cooked through.
«You could add yoghurt to either of the marinades, which gives an interesting extra flavour and soft texture when grilled.»