Peel the aubergines if desired, cut them in half and then into strips. Place in milk for approx. 1 hr. (so that all of the aubergines are covered). Remove the aubergines from the milk, immediately roll in the croûtons and place on a baking tray lined with baking paper.
To bake: approx. 15 mins. in the centre of an oven preheated to 220 °C (they should be golden-brown and crispy on the outside but still soft on the inside).
Serve while still warm together with the sauce.
Grate the cucumber straight into the yoghurt, stir in the lemon zest and juice, olive oil and garlic, season the sauce.