In a mixing bowl, combine oil, Sriracha, freshly ground pepper, and soy sauce to create a flavorful marinade for your steak strips. Ensure the steak is well-coated, cover the bowl, and let it marinate for at least 30 minutes at room temperature.

Heat a skillet over medium-high heat and add a tablespoon of butter. Season the marinated steak strips with salt and additional pepper, then place them into the hot skillet. Sear the steak for 1-2 minutes on each side until a golden crust forms.

Lower the heat to medium and add a bit more butter to the skillet. Once melted, add finely chopped shallots and minced garlic. Sauté for about 2 minutes until the shallots are soft.

Add fresh thyme, chopped chives, chili flakes, lemon juice, mustard, and beef stock. Scrape up browned bits from the skillet and allow the mixture to simmer for about 5 minutes or until it reduces by half.

Incorporate remaining butter, taste to adjust seasoning. Return seared steak to the pan, heating in the sauce for about a minute, then plate the steak and drizzle with the silky butter sauce.