1 ½ pounds Idaho/Russet potatoes (these are best for fries because they’re starchy!)
3 tablespoons extra virgin olive oil
1 teaspoon kosher salt, plus more to taste
1 teaspoon paprika
¼ teaspoon cayenne, plus more to taste
Chopped fresh parsley and Parm for serving
Preheat the oven to 400°F.Heat the oil in a 10-inch skillet over medium-high heat. Add the onions and cook, stirring, until lightly golden, 8 to 9 minutes. Add the garlic and cook, stirring, 1 more minute. Add the ground beef and cook, stirring and breaking up the meat with a wooden spoon, until just cooked through, 5 to 6 minutes. Add the tomato paste, salt, sugar, oregano, and chili flakes and cook, stirring, until absorbed into the meat, 2 minutes. Add the crushed tomatoes and water, bring to a low boil, reduce the heat to low and simmer, stirring once in a while and adding water by the tablespoonful if necessary, until a thick sauce forms, 15 to 20 minutes. Season with more salt and chili flakes to taste. Cover with foil to keep warm.
While the sauce is simmering, cut the potatoes into ½-inch-thick matchsticks. Whisk the oil, salt, paprika, and cayenne in a large bowl, add the potatoes and toss to coat. Pour onto a large rimmed baking sheet, spreading out as evenly as possible. Bake until the potatoes are crisped and the undersides are a deep golden brown, 20 to 25 minutes.
Dollop the sauce right over the potatoes on the sheet pan and garnish with parsley and Parm. Let people lift up servings with a wide spatula.