Heat the oil in a saucepan over a medium heat and cook the garlic for 2 mins until fragrant, then stir in the tomato purée, oregano and a pinch of sugar. Cook, reducing the heat if needed, for 4-5 mins more until the purée is caramelised and darkened. Add the roasted veg, stock, orzo and sweetcorn. Bring to a simmer and cook for 8-10 mins until the orzo is just al dente.

Meanwhile, combine the feta, olives, parsley and lemon zest in a small bowl and season with pepper.

Season the soup to taste and serve with the feta and olive mixture scattered over the top.