1. Preheat oven to 450°F. Toss together carrots, 2 tablespoons oil, cumin seeds, 3/4 teaspoon salt, and 1/4 teaspoon pepper on a large rimmed baking sheet; spread in an even layer on half of baking sheet. Roast in preheated oven until carrots are lightly browned, about 10 minutes. Remove from oven.
2. Brush steak pieces evenly with remaining 1 tablespoon oil; sprinkle with remaining 1 teaspoon salt and remaining 1/4 teaspoon pepper. Arrange steak evenly on empty half of baking sheet. Return to oven; roast at 450°F until carrots are just tender and a thermometer inserted in thickest portion of steak registers 125°F, about 7 minutes. Transfer steak to a cutting board; let rest 5 minutes. Thinly slice steak against the grain.
3. Divide steak slices and carrots among warm tortillas. Serve with sour cream, cilantro, jalapeños, and lime wedges