Peel onion, then cut in half horizontally. With the cut side down, slice each half into 1/2" wide strips.
In a large skillet heat 3 tablespoons vegetable oil over medium-low heat. Add sliced onion and cook till softened, about 4 minutes. Add garlic, stirring occasionally for 30 seconds, then stir in mushrooms. Continue to cook till mushrooms are shrunken down and golden in color, about 8 minutes, stirring occasionally. Remove mixture to a bowl and set aside.
Add the remaining 1 tablespoon vegetable oil to the pan and raise heat to medium-high. Once oil is hot, add chicken and cook till chicken is browned and cooked through, about 6 minutes, stirring frequently. Add Alderwood smoked salt, Khmeli Suneli, paprika and black pepper and stir well, cooking for 30 seconds. Stir in flour, tossing so all ingredients are covered well, then add chicken broth. Be sure to scrape the bottom of pan well, to loosen any browned bits. Stir in reserved vegetables, cover loosely, and simmer on low for 20 minutes, stirring occasionally, especially near the end, to prevent sticking. Remove from heat and stir in sour cream and roasted walnut oil. Serve over egg noodles with another drizzle of walnut oil.