Preheat your oven to 180°C/Fan 160°C/ Gas 4. Peel and finely chop the red onion. Peel and grate the garlic cloves.

Warm a medium pan on a medium heat for a few mins. When warm, drizzle in 1 tbsp olive oil and add the onion. Season with salt and pepper. Gently cook for 5 mins till glossy. Stir in the garlic and 1 tsp dried oregano and cook for 1 min more. Pour in the tin of chopped tomatoes and add 1 tbsp balsamic vinegar (keep the rest for later). Pop a lid on the pan (or use a baking tray if you don’t have a lid) and simmer for 15 mins, stirring now and then.

While the tomato sauce is cooking, slice the courgettes lengthways into thin strips. You should get 6-8 slices per courgette.

Heat a dry frying or griddle pan till smoking hot. Lay some courgette slices in the pan (no need for oil). Cook for 2 mins on each side. They should be slightly charred and softened. Lift out onto a plate. Repeat with the remaining courgettes.

Tear the mozzarella ball into small pieces. Pick the mint leaves and finely shred them. Taste and season the tomato sauce. Spoon a quarter of the sauce into a medium-sized ovenproof dish. Lay some courgette slices on top to cover the sauce. Scatter a quarter of the mozzarella over the courgette. Sprinkle over some mint leaves.

Keep repeating the layers, finishing with a scattering of mozzarella (keep a pinch of mint back for garnishing). Scatter over the breadcrumbs and finish with a good crack of black pepper. Slide into the oven for 30 mins till the top is golden and the mozzarella has melted.

While the courgette gratin cooks, whisk 1 tbsp balsamic vinegar with ½ tbsp olive oil and some salt and pepper.

Remove the gratin from the oven. Leave to rest for a couple of mins. Meanwhile, toss the rocket with the balsamic dressing. Scatter the remaining mint over the gratin and serve it with the rocket salad.