Use a spiralizer or vegetable peeler to create noodles out of the zucchini. Set aside.
In a medium saucepan over medium-high heat, heat the oil and cook the sausage, onion and garlic until the sausage is cooked through and the onion is soft, about 5-7 minutes.
Add the oregano and cook for 1 minute. Add the flour and stir until everything is well coated.
Add the milk and bring to a simmer. Cook, stirring constantly, until the sauce thickens, about 5 minutes.
Remove from heat and mix in the sour cream, parmesan cheese and black pepper. Season with salt to taste.
Add the zucchini to the pot and toss to coat. The heat from the sauce will soften the zucchini a bit. Serve.