In a small bowl, combine all of the Talatouri ingredients. Set aside.
Prepare your sandwich ingredients: tomato, lettuce, olives, oregano, bread, red onion.
Get yourself a pan and place it on medium heat. Drizzle over some olive oil and add in your sliced halloumi. Fry on each side for 4 minutes or until golden. Remove the halloumi ready to assemble your sandwich.
Time to assemble your sandwich. Lightly toast your bread and then spoon on your Talatouri. Layer on your halloumi, red onion, tomato, olives, oregano, lettuce, and your second piece of bread. Serve up and enjoy!