2 portobello mushrooms, wiped clean and stalks removed
2 tbsp finely chopped cucumber
4 romaine lettuce leaves, roughly torn
1 lime, juice only
2 tbsp finely chopped fresh mint
2 tbsp finely chopped onion
2 tbsp finely chopped tomato
1 large tomato, thickly sliced
salt and freshly ground black pepper
2 tbsp olive oil
200g/7oz halloumi cheese, thickly sliced
4 tbsp hummus
2 brioche buns, cut in half