Heat your oven to 180°C/Fan 160°C/Gas 4. Halve the aubergines. Score a criss-cross pattern into the cut side of the aubergines. Place them in a roasting tin. Brush them with 1/2 tsp oil each and season with salt and pepper. Roast for 20 mins.
While the aubergines roast, finely dice the tomatoes and tip them into a bowl. Halve the chilli, scoop out the seeds and white bits (or leave them in for extra heat). Finely chop it. Peel and crush the garlic. Add them both to the tomatoes.
Chop the halloumi into 1/2cm-big cubes. Stir them into the tomatoes with a crack of pepper. Set aside.
Finely chop the mint leaves and put most of them in a small bowl (save a pinch for garnishing). Finely grate in the lemon zest. Juice it. Add the tahini and 3 tbsp water and stir together to combine. If you have a small food processor or blender, you can whizz them all together for a smoother sauce.
After the aubergines have roasted for 20 mins, take them out of the oven. Spoon the tomatoes and halloumi over the top. Return to the oven and bake for another 20 mins till the aubergines are golden and tender. Toss the salad leaves with 1 tbsp balsamic vinegar.
Serve the aubergines drizzled with the minted tahini sauce and the salad on the side. Scatter over the last of the mint leaves to garnish.