Cook the pasta: Bring a large pot of salted water to a boil and cook your pasta according to the package directions. Before draining, reserve ¼ cup of the pasta water — that starchy liquid is going to help bring the sauce together.
Brown the onion and vegan beef: While the pasta cooks, heat the oil in a large saucepan over medium-high heat. Add the onion and Beyond Beef and break it apart with a spatula or wooden spoon. Cook for about 7 to 9 minutes, stirring frequently, until the vegan beef starts to brown.
Make it creamy and flavourful: Add the garlic, mushrooms, nutritional yeast, half the red wine vinegar and coconut milk (or cashew cream). Stir everything together, cover the pan and bring it to a boil. Reduce the heat to medium and let everything simmer for about 10 minutes, stirring occasionally, until the mushrooms have softened and the sauce has thickened slightly.
Bring it all together: Add the cooked pasta, reserved pasta water and vegan sour cream, plus more to taste, to the sauce. Season generously with salt and black pepper and stir until everything is beautifully coated in that creamy sauce.
Turn off the heat and let the stroganoff sit uncovered for about 5 minutes, stirring once or twice. This gives the sauce a chance to thicken up and cling tenaciously to every delicious noodle.
Spoon into bowls and garnish with fresh parsley and, of course, plenty of freshly cracked black pepper. Because when it comes to stroganoff, there is no such thing as too much black pepper.
