Using a meat tenderizer or rolling pin pound chicken to an even 1-2 cm thickness.
In a large bowl or ziplock bag combine 3 tablespoons canola oil, lime juice, garlic cloves, paprika, sugar, salt, cumin, pepper and cayenne.
Add chicken to the marinade and massage if desired, cover or zip and let stand at room temperature for 30 minutes or in the refrigerator 1-2 hours.
While chicken is marinating prepare your onions and peppers in thin slices or give diced vegetables a try.
Preheat oven to 300 degrees.
Heat your skillet over medium high heat and add 1 tablespoon of oil. Remove chicken from the marinade (discard any remaining marinade) and cook without moving until bottom side is well browned and starting to cook through. Flip chicken over and transfer skillet to the oven to bake for 15-20 minutes until chicken registers 160 degrees.
Transfer chicken to a cutting board and let rest 5 minutes. If making ahead of time skip next step and instead add sliced chicken and raw vegetables to your skillet, cover and store in the refrigerator until just before dinner and follow the final step.
Heat your skillet over medium high heat and cook onions and peppers for 3-4 minutes.
Slice chicken crosswise into 1 cm thick strips and transfer back to your skillet.
Heat chicken and vegetables over medium high heat and serve with warmed tortillas and your favourite toppings.