In a medium saucepan, bring potatoes and water to cover by 2 inches to a boil over medium-high heat. Cook until just tender, about 5 minutes; drain in a colander, and set aside.
In the same saucepan, add tomatoes, 1⁄4 cup water, oregano, 1⁄4 teaspoon salt, paprika, 1⁄4 teaspoon black pepper, cumin, and red pepper. Bring to a simmer over medium heat. Reduce heat to medium-low; partially cover and simmer for 5 minutes. Cover and set aside.
In a 10-inch cast-iron skillet, heat oil over medium-high heat. Add sausage and onion. Reduce heat to medium; cook until sausage begins to brown, about 3 minutes. Add potatoes, garlic, remaining 1⁄2 teaspoon salt, and remaining 1⁄4 teaspoon black pepper; cook until lightly browned, about minutes. Pour tomato sauce over potatoes. Make 4 indentations in mixture; crack 1 egg into each.
Bake until eggs are just set, about 12 minutes, or until desired degree of doneness. Sprinkle with queso fresco. Let stand for 5 minutes before serving. Garnish with parsley and additional pepper, if desired.
Recipe by Southern Cast Iron at https://southerncastiron.com/skillet-fries-sausage-baked-eggs/