Layer the aubergine slices in a colander, sprinkling each layer with salt. Leave to stand for 30 minutes. Rinse thoroughly to remove all the salt and pat dry on kitchen paper.
Process the garlic, harissa paste, ground spices, lemon juice, coriander, mint and 75 ml (3 fl oz) of the olive oil in a food processor to make a thin paste.
Brush the upper rack of the halogen oven lightly with some of the remaining oil and lay the aubergine slices on it. (You will need to cook the aubergines in several batches.) Brush with more oil and cook for 5–6 minutes, turning once and brushing with more oil, until tender. Keep warm while cooking the remainder.
Arrange on a serving plate, drizzle with the sauce and garnish with chopped parsley.