Heat the oil in a large saucepan. Add the onion and beetroot, and cook over a low-medium heat for 15 mins. Add the garlic and cook for 1 min. Stir in the rice and fry for a couple of minutes, then pour in the wine and bring to a simmer. Add half the stock, stirring until it is absorbed. Add the remaining stock, a ladleful at a time, stirring continuously until the rice is al dente. Stir through the parmesan and lemon juice, adding a splash more stock to loosen if the risotto seems a little thick. Season to taste.

Toss the feta with the lemon zest and dill, if using, and spoon over the risotto. Finish with a drizzle of olive oil. Any leftovers will keep covered in the fridge for up to three days. Reheat in a pan over a low heat, stirring in a little stock to loosen.