Heat the oil and/or butter in a wide 4-quart/4-l pot over medium-low heat. When almost hot (do not allow the butter to burn), add the onion and sauté until it is translucent. Stir frequently. Add the rice and continue stirring so that the rice toasts. It should become opalescent after a couple of minutes.
Pour in the wine and cook, stirring, until the wine has evaporated.