Preheat your oven to 400°F and place a cast-iron skillet inside to heat up.
Pat the skirt steak completely dry with paper towels to ensure a deep, savory sear forms during cooking.
Rub the steak with 0.5 tablespoon of olive oil and season both sides evenly with sea salt, black pepper, garlic powder, and onion powder.
Carefully remove the hot skillet from the oven and place it on the stove over medium-high heat.
Sear the steak for 2 minutes per side until a golden-brown crust forms.
Transfer the skillet back into the oven and roast for 3 to 4 minutes for medium-rare doneness.
While the steak cooks, halve the cherry tomatoes and thinly slice the red onion.
In a small bowl, whisk the remaining 0.5 tablespoon of olive oil with the red wine vinegar and dried oregano.
Toss the tomatoes and onions with the prepared dressing in a medium mixing bowl.
Remove the steak from the oven and let it rest on a cutting board for at least 5 to 7 minutes to retain its juices.
Slice the skirt steak thinly against the grain and serve alongside the fresh tomato salad, garnished with chopped fresh parsley.