Pre-heat the oven to 220 °C (200 °C fan)
Cut the aubergines into thick slices, spread them out on a parchment-lined baking tray and drizzle generously with olive oil and 1/3 tsp salt on each side. Roast for 40 minutes, turning halfway through, until golden.
To make the tahini dressing, stir together the tahini and lemon juice with a pinch of salt and a splash of water. If it’s too thick, keep adding splashes of water until you can drizzle the tahini from the spoon. If it’s too thin, add more tahini, always balancing it with lemon juice.
Make a green sauce by bashing a garlic clove with 1/3 of salt in a pestle & mortar. Add the leaves of the coriander and continue pounding. Once broken down into a paste add the extra virgin olive oil and the red wine vinegar. It should be runny enough that you can drizzle it from a spoon so add more oil if needed.
Add the cherry tomatoes, the cucumber, the shallot, the mint leaves and the lemon juice into a bowl and toss together along with 1/3 tsp salt.
Cut the focaccia slices in half and grill in a griddle pan until charred. Then build your sandwich. Start with the green sauce followed by a few aubergine slices, the salad, the tahini dressing, a few more aubergine slices and a bit more green sauce. Close the sandwich and enjoy.