Prepare the Shredded Beef:
Heat olive oil in a skillet over medium-high heat. Season the beef with salt and pepper, then sear on all sides until browned, about 2-3 minutes per side.
Transfer the beef to a slow cooker. Add onion, garlic, beef broth, chili powder, cumin, smoked paprika, and oregano. Cover and cook on low for 8 hours or high for 4 hours, until the beef is tender.
Remove the beef from the slow cooker and shred it using two forks. Return the shredded beef to the juices in the slow cooker to keep it moist.
Preheat the Oven:
Preheat your oven to 375°F (190°C).
Assemble the Enchiladas:
Spread 1/2 cup of enchilada sauce on the bottom of a 9x13-inch baking dish.
Warm the tortillas to make them pliable. Spoon shredded beef and a sprinkle of cheese into the center of each tortilla. Roll tightly and place seam-side down in the baking dish.
Pour the remaining enchilada sauce over the rolled tortillas and sprinkle the top with the rest of the cheese.
Bake:
Cover the baking dish with foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and slightly golden.
Serve:
Let the enchiladas cool slightly before serving. Garnish with sour cream, jalapeños, and cilantro if desired.