Pound out the thicker end of the chicken breast to make the thickness even on both ends, about 1/2-inch thick, this will ensure the chicken cooks even. Use the tenderizer to tenderize the breast (this is optional, but will give you the most tender chicken breast).
Add chicken to a shallow bowl and pour enough pickle juice to cover. Cover and refrigerate at least 4 hours, or up to 8 hours.
Make the spicy mayo: Combine mayo and sriracha, set aside.
In a medium bowl whisk vinegar, 1 teaspoon olive oil, Dijon and 1/8 teaspoon salt. Add cabbage and carrots and toss to combine. Cover and chill until ready to assemble sandwiches.
When ready to cook, preheat the grill on high.
Combine garlic powder, paprika, cayenne pepper and 1/4 teaspoon salt in a small bowl. Rub chicken on both sides with olive oil spray then spread the spices all over both sides.
When the grill is hot, reduce heat to medium-low, oil the grates and add the chicken.
Cook 4 to 5 minutes on each side, or until an instant-read thermometer inserted into the thickest part of the breast reads 165F, careful not to overcook so you don’t dry out the chicken.
To assemble sandwiches, place the spicy mayo and slaw on both sides of the rolls. Add the chicken and pickle slices.