Heat an indoor or outdoor grill to medium. Cook the sausages until cooked through. Remove from grill and slice into 1/2-inch pieces. Set aside.
Bring a large pot of water to a boil. When boiling, salt generously and add the orzo. Cook until al dente and drain.
In a large skillet, heat the olive oil. Add the onion and cook until translucent. Add the garlic and cook 1 minute more. Add in the zucchini and mushrooms and cook for 5-7 minutes. Season with salt and pepper.
Add the cooked orzo into the vegetables. Sprinkle on the Parmesan and stir well. Add in the sausages and squeeze the lemon juice over the top. Serve.