Preheat the oven to 240°C.
Place the cauliflower in a large bowl with the olive oil. Season to taste and toss to combine. Roast for 20-25 minutes until browned.
Meanwhile, for the onion and burnt honey vinaigrette, place the honey in a small non-stick saucepan over a medium- high heat and cook for 2-3 minutes until it starts to darken and caramelise. Add the onion, lower the heat and cook down until the onion has begun to soften. Remove from heat, add vinegar and oil, season to taste and cool. Set aside.
Transfer the roasted cauliflower in a large bowl with half of the vinaigrette. Season to taste and toss to combine. Transfer to a large platter and drizzle over remaining vinaigrette. Scatter over haloumi and za’atar to serve.
