Put the dry pearl barley in a saucepan, and cover with cold water, or vegetable stock if preferred. Bring to a boil, then reduce heat and simmer for 1 hour 15 mins or until tender.
Generously season the aubergine slices with salt. Place them in a colander. Let stand 15 to 30 minutes, then pat dry with a paper towel.
Heat the oven to 200°C. Put the red pepper and cherry tomatoes on a baking tray with a tablespoon of olive oil and some salt and pepper. Place in the oven for 30 minutes.
Heat a griddle or frying pan over a high heat with the other tablespoon of olive oil. Griddle the aubergine and halloumi cubes in batches until cooked. The aubergine will take about 5 minutes on each side and the halloumi just needs to be crisped to your liking.
Once the barley is cooked stir through the chopped herbs and a squeeze of lemon juice. Serve a helping of the barley with a couple of slices of aubergine, some cubes of halloumi and the roasted veg along with a lemon wedge.