1. Cook the whole aubergine on a hot barbecue or on a grill pan, turning every 10 minutes or so until charred, and soft on the inside when pierced. This will take about 35 minutes.
2. While the aubergine is cooking, make the tahini sauce. Add all the ingredients into a medium bowl and stir with a fork until well combined.
3. Once the aubergine is cooked, remove from the barbecue and place in a bowl covered with a plate. Once cool enough to handle, peel the skin off, leaving the stalk attached. Cut in half lengthways, keeping the top of the aubergine attached to the stalk, and place on plate, spreading out the two halves. Make a few more cuts along the length of the aubergine to make it easy to serve.
4. Drizzle with the tahini sauce and sprinkle with your preferred garnish. Serve with pita bread.