Trim the ends off the aubergines then cut lengthways into 1cm-long strips. Season with salt and leave for 20 minutes whilst you make the sauce.

Finely chop the onion and garlic cloves. Get a small saucepan over
a medium heat. Drizzle in a good glug of olive oil. Scrape in the onion along with a pinch of salt and fry, stirring occasionally, until completely soft. Add the garlic and chilli flakes and fry, stirring for 30 seconds, then tip in the plum tomatoes. Use the back of your spoon to break up the tomatoes, add the sugar then lower the heat and leave the sauce to simmer away.

Spoon the flour out onto a plate. Lightly coat half the aubergine
slices in the flour – this will help make them jammy and soft without
absorbing too much oil. Get a large non-stick frying pan over a medium–high heat, drizzle in a good amount of oil then place half the floured aubergine slices in the pan. Fry for 6–8 mins, turning halfway, until golden and soft. Transfer to a plate then repeat with the remaining aubergine.

Preheat your grill to high. Slice the rolls three-quarters of the way
through the centre, opening them up slightly so you can fit in the most amount of filling. Season your sauce with salt and black pepper and stir through most of the basil leaves.

Assembly time. Thinly spread sauce over the bottom of each sub.
Layer up the aubergine, more sauce and mozzarella, tearing the cheese in as you go, making sure to finish with a layer of mozzarella. Finely grate over the Parmesan. Season with black pepper then slide under the hot grill until golden and bubbling. Tear over the remaining basil leaves and drizzle with a little more oil to serve.