Heat the oil and butter in a heavy saucepan and sauté the onions, at low temperature, until translucent.
Add the rice stir over medium temperature for 1-2 minutes. Pour over the wine and stir until the wine has absorbed.
Add the vegetable stock to the rice , ladle by ladle after the liquid has absorbed, while continuously stirring.
After 15-20 minutes taste the rice. It is good when the rice al dente.
Meanwhile, steam your chosen vegetables in a steamer and immediately transfer them to cold water.
When the rice is done, stir in the lemon zest and juice, then the grated Parmesan and finally the steamed vegetables. Allow to rest for 5 minutes under cover.
Serve warm, pronto.