In a small bowl, combine 2 tablespoons oil, lime juice, garlic, cumin and oregano. Pour half in a large bowl or dish; add chicken and turn to coat. Marinate for at least 30 minutes. Cover and refrigerate remaining marinade., In a large skillet, heat remaining oil on medium-high. Saute onion for 2-3 minutes or until crisp-tender. , Drain chicken, discarding marinade. Add chicken to skillet; stir-fry until meat is no longer pink. Add the red pepper, chiles and reserved marinade; cook 2 minutes or until heated through. Stir in almonds. Serve immediately over shredded lettuce; top with tomatoes and avocado.