Season the cubes generously with salt and freshly ground black pepper.
Heat your largest skillet over high heat until screaming hot. Pour in the 3 tablespoons olive oil.
Add the steak cubes in a single layer to the hot skillet, working in batches, if necessary, to avoid overcrowding the pan.
Sear the steak bites for 2 to 3 minutes per side until they develop a nice crust. Transfer the bites to a bowl and cover with foil.
Make the garlic butter sauce
In the same skillet, reduce the heat to medium-low. Add the 4 tablespoons (2 oz) unsalted butter and let it melt.
Add the minced 6 cloves garlic (plus the 1 tablespoon fresh rosemary and 1 tablespoon fresh thyme, if using). Sauté, stirring frequently, for about 1 minute, until fragrant.
Combine and finish
Return the steak bites to the skillet and toss them in the garlic butter sauce. Cook for a minute or two until the steak bites are warmed through and coated in the sauce.
Garnish with chopped fresh parsley. Serve immediately.
Notes
Prep before you cook--Before you begin cooking, have all of your ingredients ready and nearby. Once you add the steak to the skillet, it cooks quickly.
Use a hot skillet--Let your skillet get very hot before adding the oil and steak. This will allow it to quickly develop a seared crust without overcooking.
Cook it to a perfect medium-rare--If you like medium-rare steak, freeze the cubes for 10 minutes or so while the skillet gets screaming hot. Then, pop the cold, seasoned bites into the pan and cook quickly.