Pat the sirloin or ribeye steak dry with a paper towel, then cut it into ½-inch thick strips or 1-inch cubes as preferred. Season the beef with 1/2 teaspoon of seasoned salt and 1/2 teaspoon of black pepper. Toss the beef with 1 tablespoon of all-purpose flour, ensuring all pieces are lightly coated. Shake off any excess flour before cooking.

Heat 2 tablespoons of olive oil in a large skillet or Dutch oven over medium-high heat. Working in small batches, brown the floured beef on each side for about 1 minute until lightly browned, but not fully cooked through. Transfer each batch of browned beef to a plate and set aside.

Reduce the heat to medium. Add 2 tablespoons of salted butter to the skillet, then add the diced onion. Sauté until the onion is softened, about 4-5 minutes. Add the sliced mushrooms and minced garlic; continue to cook until the mushrooms are softened, about 4 minutes. Stir occasionally to prevent sticking.

Sprinkle the remaining 2 tablespoons of all-purpose flour over the cooked mushroom mixture and stir well. Cook for 1 minute to eliminate the raw flour taste. Then, pour in the beef broth, Worcestershire sauce, Dijon mustard, and dried thyme leaves. Bring the mixture to a boil while stirring to prevent lumps, then reduce the heat and let the sauce simmer, uncovered, for 5 minutes to thicken.

Return the browned beef and any collected juices from the plate to the skillet with the thickened sauce. Cook for 2 additional minutes, just until the beef is heated through. Remove the pan from the heat and immediately stir in the sour cream until the sauce becomes creamy. Taste and adjust seasoning with additional salt and pepper if desired. I like to let the dish rest for a couple minutes off the heat so the beef stays tender.

Serve the creamy beef stroganoff over cooked egg noodles, pasta, or mashed potatoes as desired. Garnish with chopped fresh parsley if you have it on hand for a touch of color and fresh flavor.