Heat the olive oil in a large, heavy-based frying pan, add the onion, leek, mushrooms, and garlic and cook over a medium-high heat for 5–6 minutes until softened and golden in places. Add the rice and stir well, then add the stock and wine, reduce the heat to a gentle simmer and cook, stirring frequently, until the liquid is almost all absorbed and the rice is tender and cooked through, adding more stock if necessary.
Remove the pan from the heat and leave to cool for 20 minutes. The mixture will not only cool but more liquid will be absorbed and the rice will become a little more stodgy.
Divide the mixture into 8 and mould each portion into a large patty, then toss liberally in the cornmeal and set aside.
Heat the sunflower oil in a frying pan and cook the cakes over a medium-high heat for 2–3 minutes on each side until golden and crisp. Serve hot with a simple dressed salad.