Heat the oil in a pan. Sauté the onion, add the rice and tomato puree, sauté until the rice is translucent, stirring constantly. Pour in the wine and reduce completely. Gradually add the stock, stirring frequently, so that the rice is always just covered with liquid, simmer for approx. 25 mins. until the rice is creamy and al dente. Stir in the cherry tomatoes after 15 mins. Stir in two-thirds of the parmesan, season. Plate up the risotto, garnish with the remainder of the parmesan and thyme.