Make the pickled onions first: toss sliced onions with salt and lemon juice. Squeeze the onions a bit as you toss. Let them steep until you need them. This can be made up to 2 weeks in advance and refrigerated.
Make the whipped paneer: bring the milk up to the boil. Take off the heat and add lemon juice. Stir for 2-3 mins until it starts to curdle and the whey separates from the fats.
Strain the paneer in a strainer or in a piece of muslin. Retain the whey. We don’t want the paneer too dry, so strain quickly and add to a blender jar. Add salt and blend until smooth. You want the texture of hummus. Add a bit of whey to get this consistency. Set aside.
Turn two burners up full throttle. Place one aubergine over each burner and roast until charred and blistered on all sides. Use tongs to turn them around every so often. Make sure to also char the tops and bottoms. The more blackened they are, the better their flavour. Add to a bowl, clamp on a lid, and let them steam for 10 mins.
Meanwhile make the dressing: add all the ingredients to a plate and mix to combine. Taste and adjust seasoning.
Remove the aubergines from the bowl and flake off their charred outer skins. Place one on a chopping board and halve it lengthwise keeping the stalk intact.
Open it out and then slice each half lengthwise again - essentially leaving you with 4 parts (refer to pic above). Repeat with the other aubergine. Coat the aubergines in the harissa dressing.
To assemble: dollop the whipped paneer onto a plate. Place the aubergines on top and spoon over all the remaining dressing over them. Top with pickled onions and serve with pitas/flatbreads to mop it all up with.