Slice 2 of the garlic cloves and mix together with 2 tablespoons olive oil, the chilli, orange rind and juice, fennel seeds and olives. Place on a small baking sheet and cook in a preheated oven, 200°C (400°F), Gas Mark 6, for 15 minutes.
Meanwhile, cook the potatoes in a large saucepan of boiling water for 10 minutes, then add the beans and cook for 3–5 minutes more until soft. Drain and cool under cold running water. Heat a griddle pan until smoking. Pat the haloumi dry and griddle for 2–3 minutes on each side until golden and lightly charred.
Crush the remaining garlic and whisk together with the vinegar and the remaining olive oil. Toss the dressing together with the potatoes and beans, tomatoes and onion. Arrange on a plate with the haloumi slices, drizzle over the warm olives and marinade, then scatter over the oregano to serve.