Prepare the slow cooker. Spray a 4- or 5-quart slow cooker with cooking spray. A 6-quart slow cooker may also be used, but the chicken may cook more quickly.
Mix the seasonings. In a small bowl, combine the smoked paprika, black pepper, salt, garlic powder, onion powder, red pepper flakes, and thyme.
2 tsps smoked paprika, ½ tsp black pepper, 1 tsp salt, ½ tsp garlic powder, ¼ tsp red pepper flakes, ½ tsp dried thyme, ½ tsp onion powder
Add the vegetables. Place the sliced bell peppers and onion in the bottom of the slow cooker. Sprinkle 1 teaspoon of the seasoning mixture over the vegetables.
2 green bell peppers, 1 large yellow onion
Season the chicken. Place the chicken in a gallon-size zip-top bag. Add the steak sauce and toss to coat. Add the remaining seasoning mixture and toss again until the chicken is evenly coated.
2 pounds boneless skinless chicken breasts, 3 Tbsps steak sauce
Add to the slow cooker. Place the seasoned chicken over the peppers and onions. Pour the chicken broth around the edges.
½ cup low-sodium chicken broth
Cook the chicken. Cover and cook on LOW for 4 to 5 hours, or until the chicken reaches an internal temperature of 165°F. Begin checking earlier if using a 6-quart slow cooker; the chicken may be done in about 3 hours.
Shred the chicken. Transfer the chicken to a cutting board and shred with two forks. Tent loosely with foil and set aside.
Drain the vegetables. Using a slotted spoon, remove the peppers and onions from the slow cooker. Pour the cooking liquid into a measuring cup and reserve.
Combine the filling. Return the shredded chicken, peppers, and onions to the slow cooker. Add about ¼ cup of the reserved cooking liquid, or just enough to keep the chicken moist. Add more as needed. Keep warm until ready to serve.
Assemble the sandwiches. Toast the hoagie buns under the broiler. Spoon the chicken and pepper mixture onto the bottom halves and top with provolone. Broil just until the cheese is melted and bubbly.
Sliced provolone, Hoagie buns
Serve. Spread mayonnaise, mustard, or Thousand Island dressing on the buns, if desired. Close the sandwiches and serve immediately.
Mayonnaise, Mustard, Thousand Island Dressing