MIX all the marinade ingredients together in a large bowl. ADD the chicken, MIX well, COVER and let MARINATE in the fridge for 1 hour. (You can marinate chicken in the fridge for up to 8 hours but no longer than that.)
REMOVE the chicken from the marinade.
HEAT a large metal skillet on high heat for 1-2 minutes. ADD 1 Tablespoon of canola oil (or other high smoke point oil) to the pan.
When oil begins to smoke, ADD chicken pieces to the pan. Depending on size of pan, you may have to work in batches (Don't crowd the chicken or it wills steam instead of grill). COOK chicken undisturbed for 2-3 minutes, until you have a good sear. TURN the pieces over and COOK for another 2-3 minutes until well seared on the other side. REMOVE from pan.
ADD peppers and onions to the pan and grill until onions are opaque in color (nearly clear looking).
SERVE chicken with sautéed pepper and onions in warm tortillas. TOP with your choice of shredded cheese, salsa, guacamole, and/or thinly sliced iceberg lettuce.