Combine onion and butter in 4-quart microwave-safe deep casserole. Microwave, uncovered, on high power for 5 minutes.

Stir in rice to coat. Microwave, uncovered, on high power for 2 minutes.

Add wine, vegetable broth, salt and saffron if using; stir to combine. Cover with microwave-safe plastic wrap, venting slightly, at one corner. Microwave on high power for 15 minutes; stir. Microwave, uncovered, on high power for 10 minutes.

Add sausage slices and asparagus pieces; stir to combine. Microwave uncovered, on high power for another 2 minutes or until all liquid is absorbed and sausage and asparagus are heated through.

Stir in Parmesan cheese. Let stand, covered, for 5 minutes. Makes 6 servings.

Conventional Cooking Method: Heat butter in large, deep saute pan over medium heat. Add onion and cook, stirring, about 5 minutes or until softened. Meanwhile, heat broth, salt and saffron in a large saucepan over medium heat. Add rice to onion and cook, stirring constantly, about 1 minute or until rice is coated. Add wine and cook, stirring, until wine is absorbed. Add 1/4 cup broth and cook, stirring, until it is absorbed. Repeat process, adding broth, until rice is tender, 20 to 25 minutes. When rice is almost done, add sausage and asparagus. Stir and cook until heated through. Stir in Parmesan cheese and serve immediately.