Preheat your oven to 425°F (220°C). Wash and peel the russet potatoes. Using a crinkle cutter, slice the potatoes into crinkle-cut fries. Rinse the fries in cold water to remove excess starch, then pat them dry with a towel.

In a large bowl, toss the fries with 1 tablespoon of olive oil, chopped rosemary, and sea salt until evenly coated. Spread the fries in a single layer on a baking sheet and bake for 25-30 minutes, flipping halfway through, until golden and crispy.

While the fries are baking, take the T-bone steaks out of the refrigerator to bring them to room temperature (about 30 minutes). Rub the steaks with the remaining 1 tablespoon of olive oil, then sprinkle both sides with dried oregano, salt, and pepper.

Heat a large skillet or grill pan over medium-high heat. Once hot, add the seasoned T-bone steaks. Cook for 4-5 minutes on each side for medium-rare, or until your desired doneness is reached. Use a meat thermometer for accuracy (135°F for medium-rare). Remove the steaks from the skillet and let them rest for 5-10 minutes before slicing.

In the same skillet used for the steaks, add the thinly sliced onions and cook over medium heat until they are soft and caramelized, about 5-7 minutes. Pour in the beef broth and Worcestershire sauce, stirring to combine. Bring the mixture to a simmer and let it reduce for about 10 minutes.

Stir in the butter until melted and the sauce is glossy. Season with additional salt and pepper if needed.

Slice the rested T-bone steaks and serve alongside the crinkle fries. Drizzle the savory onion jus sauce over the steak and fries. Enjoy your meal!