1 1/2–2 lbs sirloin or flank steak, cut into 1” cubes
1 1/2 tsp kosher salt
1/2 tsp black pepper
2 tbsp olive oil (optional, for searing)
6 tbsp unsalted butter, cut into pats
6 cloves garlic, minced
1/3 cup beef broth (or red wine)
1 tbsp Worcestershire sauce
1 tsp dried thyme (or 1 tbsp fresh)
1 tbsp low-sodium soy sauce (optional)
2 tsp cornstarch + 2 tbsp cold water (optional slurry)
2 tbsp chopped fresh parsley
Pinch red pepper flakes (optional)
Instructions
Pat the steak cubes dry with paper towels and season evenly with kosher salt and black pepper.
Heat olive oil in a heavy skillet over high heat and quickly sear steak cubes in batches 45–90 seconds per side until a brown crust forms. Transfer seared pieces to the slow cooker.
Scatter minced garlic over the steak, tuck butter pats among the meat, and pour in beef broth, Worcestershire sauce, thyme, and soy sauce.
Cover and cook on LOW for 2–3 hours or on HIGH for 1–1.5 hours, until steak is fork-tender but still holding shape.
To thicken, remove 1/4 cup cooking liquid, whisk in cornstarch until smooth, return to the cooker and turn to HIGH for 10–15 minutes, or transfer sauce to a skillet and simmer to reduce.
Taste and adjust salt/pepper. Stir in chopped parsley and a little lemon zest for brightness. Serve hot, spooning sauce over the steak bites.
