Sumac Sweet Potato Fries

Name: Sumac Sweet Potato Fries
Cuisine: American
Ingredients: 3 large sweet potatoes (2.5 pounds total), peeled and sliced into 1/2-inch-thick matchsticks; 1 tablespoon sweet smoked paprika (pimenton); 0.5 teaspoons ground cayenne pepper; 3 cloves garlic, crushed or minced; 3 tablespoons dried polenta or coarsely ground cornmeal; 0.25 cups plus 3 tablespoons extra-virgin olive oil; 2 teaspoons flaky sea salt; 1 tablespoon ground sumac (see headnote)