Step 1

Heat 2 tbsp of the oil in a large frying pan over a medium heat. Fry the aubergines for 10-15 mins until golden and softened. Remove with a slotted spoon and set aside.

Step 2

Fry the onions with the remaining oil for 7-10 mins or until softened. Add the garlic, 1 tbsp of the harissa and the coriander and cook for 1 min more. Return the aubergines to the pan with the tomatoes, lentils, olives and a can of water. Bring to a simmer and cook for 10 mins. Season, then stir through the parsley.

Step 3

Cook the sweet potatoes in a large pan of boiling lightly salted water for 15 mins. Drain and leave to steam-dry, then mash and stir through the remaining harissa. Spoon the aubergine filling into a large baking dish, scatter over half the feta and spoon over the potatoes. Scatter the remaining feta over the pie.

Step 4

Heat the grill to its highest setting. Grill the pie for 7-10 mins or until the top is crisp and golden. To freeze, leave to cool completely before portioning out into small freezerproof containers.