To prepare the chicken: Mix together salt, pepper, garlic powder, and paprika in a small bowl. Dry chicken thighs with a paper towel. Cut them into small pieces (1-2 inch cubes) and season with the salt mixture.
To cook the chicken: Heat a tablespoon of vegetable oil in a large skillet over medium heat. Sear the first half of the chicken for 3-4 minutes on each side. Place cooked chicken in a bowl. Repeat the same process with the rest of the oil and chicken. Cover the bowl with aluminum foil and set aside. Do not wash the skillet. You should be left with the remainings of the chicken and some brown spots.
To cook the vegetables: Heat vegetable oil (or butter) in the now-empty skillet. Add in onion. Cook, stirring frequently scraping the bits and pieces of chicken at the bottom of the pan, for about 5-6 minutes or until softened. Stir in the garlic and cook for 30 seconds.
Add in mushrooms and thyme and cook until mushrooms are softened, 4-5 minutes.
To make the sauce: Add flour and cook, stirring constantly, for a minute.
Pour in the wine, dijon mustard, and worcestershire sauce, chicken stock, salt and pepper. Give it a stir to combine.
Transfer the reserved chicken back into the pan. Stir to combine.
Put the lid on, bring it to a boil and let it simmer for about 15 minutes until the chicken is fully cooked.
Stir in the egg noodles and cook for 10-12 minutes or until fully cooked, keeping a close eye on it and stirring it a few times as it cooks.
Meanwhile, whisk together the sour cream and lemon juice in a small bowl.
Off the heat, add the sour cream mixture into the chicken stroganoff and give it a big stir.
Garnish with fresh thyme and parsley, ladle into bowls and serve.