1In a medium-large pot, heat the oil and butter over medium-high heat and saute the onion until it’s soft and translucent. Add the rice and cook for a minute, just to coat the grains with oil.
2If you like, add a splash of white wine and cook until it’s absorbed (some will cook off). Add about half a cup of stock and cook, stirring, until it’s absorbed. Continue adding stock a half cup to a cup at a time and cook, stirring (it doesn’t have to be constantly, just frequently) until it absorbs the liquid. When it’s all used up (it should take about half an hour) the grains should be soft. If they still have a crunchy core, just add a little more water or stock, if you have more. When the rice is cooked and it’s nice and creamy, stir in the cheese, lemon zest and juice, and butter. Stir until the cheese melts. (If you like, stir in a handful of chopped fresh spinach, parsley or basil too, and it will wilt into the risotto.)