Bring a large pot of water to a boil and salt generously. Cook your pasta according to package directions while you're preparing the sauce for the stroganoff. After draining my cooked pasta, I like to place it back in the cook pot and stir in some vegan butter to keep the noodles from sticking together until they're ready to serve.
Sauté onions: Melt vegan butter or in a skillet over medium-high heat. Add in diced onions and sauté for another 3-5 minutes, or until onions start to brown.
Cook down the mushrooms: Stir in sliced mushrooms and sprinkle with a generous pinch of salt to draw out moisture. Sauté for about 5 minutes, or until the extra moisture from the mushrooms cooks off. Then add in minced garlic and sauté for just another minute.
Cook the flour: Sprinkle flour over the mushroom mixture and stir until there is no more dry flour. Cook, stirring constantly, for about 1 minute to cook out the raw taste of the flour.
Deglaze: Pour in the dry white wine to deglaze the pan, scraping up anything that's sticking to the bottom. Simmer for a few minutes until the wine is reduced to almost nothing. (If you don't want to cook with wine, you can do the same with a splash of water or extra veggie broth.)
Make the sauce: Pour in beef-style veggie broth, then stir in Dijon mustard, paprika, and soy sauce. Stir thoroughly to make sure flour dissolves. Bring this mixture up to a boil then reduce heat to low and simmer for about 3-5 minutes to thicken and reduce slightly.
Finishing touches: Stir in the vegan sour cream. Taste and add salt and fresh-cracked black pepper to preference.
Enjoy over buttered pasta. I love to garnish with fresh chopped parsley or dill. This stroganoff also tastes delicious over rice or mashed potatoes.