Set the oven to 425℉. Halve the eggplant, then using a sharp knife make a cross-hatch pattern in the flesh of the eggplant. Rub the outside of each halved eggplant with 1 tablespoon of olive oil.
In a bowl, mix together remaining olive oil, turmeric, coriander and red-pepper flakes. Season eggplant with salt and pepper, then spoon spiced oil onto the flesh of the eggplant, place in a roasting dish and put in the oven for 25 minutes (or until eggplant is sunken and soft).
When the eggplant is soft, remove from the oven and roughly chop. Split each pita in half, fill with desired amount of arugula, then chopped eggplant and a drizzle of tahini. Serve with lemon wedges for squeezing.