Mix the chopped chilli and olive oil in a small bowl or cup and leave the flavours to deepen while you cook the cheese.
Use a non-stick frying pan without any oil, and give the cheese slices about 2 minutes a side until they're golden-brown in parts.
When all the slices of halloumi are cooked, transfer them to a couple of small plates.
Give the chilli oil a stir, spoon it over the cheese, then give a spritz of lemon.