Heat vegetable oil in a large skillet over medium-high heat until it shimmers. Add the ground beef, breaking it apart with a wooden spoon. Let it cook undisturbed for 3-4 minutes to develop crispy edges. The beef should turn deep brown with some caramelized bits sticking to the pan.

Push the browned beef to one side of the skillet and add the diced onion to the cleared space. Cook for 2-3 minutes until the onion becomes translucent and fragrant. Add the minced garlic and cook for another 30 seconds until you can smell its aroma blooming. Mix everything together.

Stir in the minced chipotle peppers, adobo sauce, cumin, smoked paprika, and oregano. Cook for 2-3 minutes, stirring constantly to prevent sticking. The spices should be fragrant and well-distributed throughout the beef.

Continue cooking for 5-7 more minutes, stirring occasionally, until the beef develops crispy, caramelized edges and most of the liquid has evaporated. The mixture should look slightly dry but not burnt. Taste and season with salt and black pepper as needed.

While the beef finishes cooking, warm your tortillas in a dry skillet for 30 seconds per side until they're pliable and lightly charred. Fill each tortilla with a generous portion of the crispy chipotle beef, then top with shredded cheese, diced red onion, and fresh cilantro.