Wash and chop onion, bell pepper and tomatoes, avocado.
Cut chicken into 1/2" slices.
Heat skillet over medium-high heat. When hot, add coconut oil, olive oil or butter and onions. Sauté until onions are soft and slightly translucent.
Add chicken, cumin, oregano and salt & pepper to the onions and continue to cook, stirring often.
When the chicken has browned, add the peppers and cook until tender.
Meanwhile, wash and shred the lettuce. Divide between four plates.
Top lettuce with a squeeze of lemon juice, tomatoes and sliced avocado.