Cut halved carrots in half again crosswise on the diagonal. Place carrots into a 2-quart baking dish and drizzle with vegetable oil; sprinkle with 5-spice powder and salt to taste. Toss lightly to coat carrots with oil and seasoning. Arrange carrots into an even layer.
Roast carrots in the preheated oven for 15 minutes; check for tenderness and stir if desired. Continue roasting until tender, 15 to 20 more minutes.