Cut chicken into bite-sized strips or cubes for faster cooking. In a large bowl, whisk together minced chipotle peppers, adobo sauce, cumin, smoked paprika, oregano, salt, and pepper. Toss chicken pieces in this marinade, ensuring every piece is well-coated. Let it sit for at least 10 minutes while you prep other ingredients.

Heat olive oil in a large skillet over medium-high heat until it shimmers. Add sliced onions and cook for 3-4 minutes until they start to soften and develop golden edges. Add minced garlic and cook for another 30 seconds until fragrant.

Push onions to one side of the skillet and add marinated chicken pieces. Don't overcrowd the pan—work in batches if necessary. Let the chicken sear undisturbed for 2-3 minutes to develop a nice crust, then stir to combine with onions. Cook for 8-10 more minutes, stirring occasionally, until chicken is cooked through and slightly charred around the edges.

Remove from heat and squeeze fresh lime juice over the chicken. Taste and adjust seasoning with salt, pepper, or more adobo sauce if desired. Warm tortillas in a dry skillet for 30 seconds per side until pliable and lightly spotted. Fill each tortilla with the smoky chicken mixture and your favorite toppings.