Slice the chicken breasts into 3/4-inch wide strips and place them in a large bowl.
Add the lime zest and juice, sugar, oregano, cayenne, and cinnamon.
Set aside for at least 30 minutes Cut the onions in half and then slice them thinly.
Cut the peppers, remove the cores and seeds, then slice them into 1/2-inch wide strips. Heat the oil in a large frying pan.
Stir fry the marinated chicken for 5-6 minutes, then add the peppers, and onions and cook for 3-4 more minutes, until the chicken strips are cooked through and the vegetables are soft and tender, but still juicy. Meanwhile, heat the tortillas in the microwave to soften them.
Spoon the chicken mixture into a serving bowl and take it to the table with the cooked tortillas, guacamole, salsa and sour cream.