Heat 2 tablespoons of olive oil in a large skillet over medium heat.
Add the diced potatoes and cook, stirring occasionally, for 5–7 minutes. They won’t be fully cooked yet, but they will finish cooking later. Remove from the skillet and set aside.
In the same skillet, add the ground beef and cook for 5–6 minutes, breaking it apart with a spatula or meat chopper, until no longer pink. Drain excess fat if necessary.
Add the diced onion, garlic, and red bell pepper to the beef. Cook for 3–4 minutes, until softened and fragrant.
Stir in the salt, black pepper, Worcestershire sauce, cumin, oregano, smoked paprika, and chili flakes. Cook for 1 minute to bloom the spices. Add the mustard and tomato sauce, stirring well to coat everything.
Return the cooked potatoes to the skillet and stir to combine. Cook for another 5 minutes to let the flavors meld.
Sprinkle the shredded cheese over the top, then cover the skillet for 2–3 minutes until the cheese melts. Remove from the heat, garnish with fresh parsley, and serve warm.