Combine seasoning for chicken. Add chicken to gallon zippered bag and sprinkle with seasoning mix. Shake around to evenly coat. Let rest while oven preheats.
Preheat oven to 325degF.
Spray baking rack with cooking oil and place on a parchment paper covered baking sheet. Add chicken to rack and put into oven to bake for 45 minutes.
Add dressing ingredients to a mason jar (or small mixing bowl) and shake to thoroughly combine. Cover and place in refrigerator until ready to put together.
Remove chicken from oven (check temp is up to 165degF internally). Allow to cool as long as you can before cutting into small pieces and add to a mixing bowl.
In a frying pan over medium-high heat, add bacon pieces and cook until crispy. Remove to paper towel covered plate and let cool.
Preheat oven to 425degF.
Open each pretzel bun and spray inside with cooking oil. Line out on a baking sheet and then place in oven to toast for 8 minutes.
Once chicken is cooled, add cucumbers, onions, bacon and dressing. Stir thoroughly to evenly coat.
Place a leaf of lettuce on bottom of bun, then top with portion of chicken salad (be generous) and then place top bun on and press down slightly. Repeat with remaining sandwiches.