Heat the barbecue with the lid down. It should come up to about 200 C/ 380 F
Rub the sweet potato in oil and salt and pepper. Lay down three layers of foil and the one piece of baking paper on top. Put the sweet potatoes side by side and hold up the sides of the foil while you add the water. Scrunch or fold the foil together to keep in the water. Put the potatoes onto the grill. Either flat or grill plate. Leave for around 30 minutes. Test by squeezing the foil and seeing if the potatoes are soft. You can take them off the grill and leave wrapped in foil to keep hot. They can't overcook. Serve with butter
Put the crushed garlic, sumac, oregano dijon and 1/2 teaspoon salt, honey and tomato paste and stir it around. Add the cleaned dried fillet into the bowl and roll around to coat. Put the meat onto the grill and shut the lid. Leave for 5-6 minutes before turning. Turn again after another 5-6 minutes and then put the lid down and leave while you prepare the feta and mushrooms. Turn after another 5-6 minutes. Keep the lid down.
Put the crumbled feta, chipotle and yoghurt into a processor or blender and puree till creamy. Taste for the amount of chilli and add more if required. Pour into a container and set aside.
Open the lid and leave the meat on the grill while you cook the mushrooms.
Prepare the mushrooms:. Drain and wash the chickpeas and set aside In a bowl mix the mushrooms with 1/4 cup of oil and a tiny bit of salt. Put all of the mushrooms onto the grill ( mine is on full) and barbecue on both sides. If you are using a flat grill watch they dont burn. Before returning the mushrooms to the used bowl add the extra oil, smoked paprika, lemon juice and salt and pepper. Stir and add the chickpeas, tomatoes, chives and the the mushrooms straight from the grill. Stir.
Test the potatoes and test the meat too. It should feel a bit like pressing your finger into the skin between your thumb and index finger. softish but firm ( A total of 25-30 minutes should be plenty.) Take off the grill to rest.
Slice the meat and serve with the potatoes and mushroom salad.