Preheat the oven to 220C, fan-forced. Line an oven tray with baking paper. Cut the capsicum and unpeeled sweet potato into 3-4cm chunks. Put on the lined tray, drizzle with 2 tsp oil, season with salt and pepper and toss to coat. Roast on the upper oven shelf for 25-30 mins until tender and lightly charred.
Step 2 — Cook rice
Meanwhile, rinse the rice until the water runs clear. Put in a small saucepan with 250ml (1 cup) water, cover and bring to the boil. Reduce the heat to low and cook for 12 mins or until tender and the water is absorbed. Turn off the heat and stand, covered, for at least 5 mins.
Step 3 — Cook haloumi
While the rice is cooking, finely chop the onion. Pick the coriander leaves and finely chop the stems. Cut the haloumi into 3cm chunks. Heat 2 tsp oil in a medium deep frypan over medium-high heat. Cook the haloumi, turning regularly, for 4 mins or until golden. Remove from the pan.
Step 4 — Start curry sauce
Heat 2 tsp oil in the same pan over medium-high heat. Cook the onion, stirring, for 3-4 mins until softened. Add the masala seasoning, tomato paste and coriander stems and cook, stirring, for 1 min or until fragrant.
Step 5 — Simmer curry sauce
Add the coconut milk and 125ml (½ cup) water to the curry mixture. Bring to a gentle simmer (it's important the curry doesn't boil or the coconut milk may separate), then reduce the heat to medium and cook, stirring occasionally, for 6-8 mins until slightly reduced. Stir in 1 tsp sugar.
Step 6 — Get ready to serve
Add the roast vegetables, haloumi and spinach to the curry sauce and stir to combine. Cook for 1-2 mins until the spinach is slightly wilted. Stir in ½ tsp white wine vinegar. Taste, then season with salt and pepper. Fluff the rice with a fork. Divide the rice and curry among bowls and scatter over the coriander leaves to serve.