Season both sides of each steak generously with the salt and black pepper. Let rest for 10 to 15 minutes.
Heat the vegetable oil in a large saute pan over medium-high heat and add the garlic. When the garlic starts to shimmer, carefully place the steaks in the pan. Cook the steaks individually if your pan won’t accommodate both steaks without touching.
Sear the steaks on each side for 7 minutes, or until the meat is dark brown on each side. Transfer the steaks to a large sheet of parchment paper.
Add the bell peppers, onions, and mushrooms to the pan and saute for 5 minutes, tossing frequently.
When the onions are translucent and the mushrooms have browned, add the wine and cook for 2 minutes more.
Place steak back in the pan with sauce and cook for 2 minutes for medium-rare.
Transfer the steaks to a cutting board and let rest for 5 minutes.
TIP: If serving family style, slice the steaks on a diagonal and transfer to a warmed serving platter. If serving individually, place each steak on a warmed plate. Spoon the sauce over the steaks.
Sprinkle with the parsley and serve.