The method of cooking the chicken is by using a 'vortex', which sounds epic (and makes the food taste epic!) but is actually just a stainless steel food bowl with the bottom cut off! Yes, it is possible to buy these, but why when you can make them at a fraction of the price, and not care when they inevitably rust or become blackened through overuse, and once you've tried this method of cooking things you'd like crispy you will definitely be using it regularly.
The principle behind the vortex, in the way I have used it here, is that the heat is funnelled up from the vortex (aka bowl with bottom cut off) which then descends around the chicken to cook it. This means the chicken doesn't burn because it doesn't have any direct heat but the way in which the heat is applied to the chicken makes it crisp up like fried chicken, no joke!!
So, for the recipe. Well, a good brining of the chicken beforehand is always a good start, use your favourite method (yoghurt, citrus/ acidic/ vinegar, milk, buttermilk, etc), as this will just improve the moistness. If you don't brine then don't worry, this cooking method is pretty good at keeping moisture in anyway in my experience.
Once brined, dip your chicken in a bowl of plain flour, then a bowl of beaten eggs, then into your 'breadcrumb mix', and I use the term breadcrumb loosely. Basically, use anything you think will make a nice, crispy, tasty, crunchy aromatic crust to your liking. In the recipe here I used a mixture of cornflakes, oats, panko breadcrumbs and salt+vinegar crisps. I whizzed this all up in the food processor but not too fine, you could just bash it all up in a freezer bag if you wanted some stress release. Once breaded, it should look like below.
Have your barbecue set up for the vortex. I did this by using a chimney starter with enough charcoal to fill the vortex. Once the coals are going and red hot with very little or no smoke coming off them then tip them into the middle of your barbecue and cover them with the vortex/ upturned bowl minus its bottom.
As I've got the Weber Gourmet BBQ System (the grate with the hole in the middle) I used this, but as long as your grate fits over the vortex then you're in business. As soon as your coals are going and the vortex is on then you're good to go, get that chicken on!
Now it's just a case of waiting for the chicken to cook. This should be about 20-40mins, depending on what cut of chicken you've used (smaller pieces like wings will take less time). Give the occasional look but not too often as it will not cook (whilst the "lookin' ain't cookin'" mantra isn't always true, it's probably more true here!). If you want to, stick a temperature probe in so you know when it's done and don't accidentally over- or under-cook it, this will be 75C or 165F.
Once cooked it's up to you how you serve it, as I'd done chicken breast we had them as chicken burgers. Served in a fluffy white bun with cucumber, lettuce and a sauce made with yoghurt, cream cheese and capers (probably could have thrown some lemon juice in there on retroflection, oh well one for next time!).