Combine all marinade ingredients in a large bowl and whisk together. Toss the steak pieces in the marinade using your hands to ensure they are well coated. Set them aside for the flavors to infuse.

Heat a large skillet over medium heat and add 1 tablespoon of olive oil and 1 tablespoon of butter. Allow the butter to melt completely before proceeding.

Add the quartered potatoes to the skillet and stir to coat them in the oil and butter. Spread the potatoes into an even layer and let them cook for 5 minutes without stirring.

Afterward, stir every 3-4 minutes for another 15-20 minutes, until they become fork-tender and perfectly crispy. Season with salt and pepper before transferring them to a bowl.

In the same skillet, add the remaining 2 tablespoons of butter, garlic, Italian seasoning, and red pepper flakes. Stir until the butter melts, then raise the heat to medium-high.

Place the marinated steak pieces into the skillet. Allow them to cook for 6-8 minutes, stirring occasionally.

For serving, choose between tossing the potatoes back into the skillet to mix with the sauce or plating the steak and potatoes separately.

Drizzle the flavorful pan sauce over, sprinkle with chopped parsley, and serve immediately.