2Melt butter in a large, heavy bottomed stock pot over medium heat. Add onion; cook until softened, 2 minutes.
3Add rice; cook until lightly toasted, 2 minutes, stirring constantly. Gradually add simmering stock, stirring continuously. Risotto will become "creamy" and slightly sticky. When almost finished, stir in zucchini, sun-dried tomatoes, and thyme, adding stock as needed and stirring continuously. When finished, the rice should be tender yet firm to the bite.