Heat oil a large skillet, over medium heat.
Add in your chicken, then cook, stirring occasionally, for about 3 minutes.
Sprinkle with taco seasoning, and continue to stir fry for an additional 3 minutes or so, until cooked through and nicely browned.
Remove chicken from the skillet, and set aside.
In that same skillet, add corn and bell peppers.
Saute for about 3 minutes, stirring constantly, just to warm through then add chicken back in.
Arrange your lettuce leaves on a large board or onto a large platter.
Add fresh squeezed lime to your mashed avocado, stir to combine well.
Add a spoonful of the limey mashed avocado, then top with chicken, bell peppers, corn, tomatoes and green onions.
Sprinkle with shredded cheese if desired and serve immediately.