01 - Heat 1 tablespoon oil in a large skillet over medium-high heat. Add diced potatoes and season with salt, pepper, and garlic powder. Cook, stirring occasionally, until golden and crisp, approximately 12-15 minutes. Remove from skillet and set aside.
02 - In a mixing bowl, combine shredded cabbage, grated carrot, green onions, parsley, mayonnaise, Dijon mustard, apple cider vinegar, salt, and pepper. Toss thoroughly until all vegetables are evenly coated. Set aside to allow flavors to meld.
03 - Heat remaining oil in the skillet. Add shredded corned beef and sauté for 2-3 minutes until heated through and lightly browned. Remove from heat.
04 - Warm tortillas in a dry skillet over medium heat for 15-20 seconds per side, or microwave wrapped in damp paper towels for 30 seconds until soft and pliable.
05 - Layer each tortilla with a base of crispy potatoes, followed by warm corned beef and a generous portion of cabbage slaw. Drizzle with sour cream just before serving.
06 - Plate assembled tacos immediately and serve with extra slaw on the side if desired.