Heat oven to 220C/200C fan/gas 7. Put the aubergine slices on a baking sheet, season, brush with oil and bake for 15 mins. Turn, spread with the harissa, and bake for another 5 mins.
Meanwhile, carefully lower the eggs into a pan of boiling water, turn down the heat and simmer for 10 mins. Run under cold water to cool, peel and put to one side.
In a bowl, mix the vinegar and agave or sugar with some seasoning, then tip in the beetroot, carrot and onion. In another bowl, mix together the yogurt, dill, garlic and seasoning. Toast the pittas and split them in half. Slice the eggs and put them inside the pittas with the spicy aubergine rounds and some of the beetroot salad. Spoon in the yogurt and serve with any of the remaining aubergine, salad and yogurt on the side.