Heat ½ tbsp oil in a large pan and fry the chorizo and potatoes for 5-10 minutes. Add the spring onions, chickpeas, spinach and 2 cloves garlic and cook for a further 2 minutes. Stir in the harissa paste with a quarter of the parsley and season.
In a food processor, whizz together most of the remaining parsley and the remaining garlic clove and oil with the white wine vinegar, capers and 1 tbsp water. Set aside.
Meanwhile, fry the sliced halloumi in a non-stick frying pan over a medium-high heat for 3-4 minutes on each side, until crisp and golden. Serve on top of the hash, drizzle over the sauce and top with the remaining parsley to serve.