Preheat your oven to 400°F and prepare a small roasting pan or oven-safe skillet.
Pat the top sirloin steak completely dry with a paper towel to ensure a savory crust forms during cooking.
Rub the steak with 0.5 tablespoon of olive oil and season both sides evenly with sea salt, black pepper, and garlic powder.
Place the steak in the oven-safe skillet over medium-high heat to sear for 2 minutes per side, then transfer the skillet to the oven.
Roast for 5 to 7 minutes until the internal temperature reaches your desired level of doneness.
While the steak roasts, dice the Roma tomatoes and thinly slice the red onion into a medium mixing bowl.
Whisk together the remaining 0.5 tablespoon of olive oil, red wine vinegar, and dried oregano, then toss with the vegetables.
Remove the steak from the oven and let it rest for at least 5 to 10 minutes before slicing against the grain.
Serve the sliced sirloin alongside the zesty tomato salad and garnish with finely chopped fresh parsley.