Wash, then slice the tomato into 6 rounds. Wash and dry the lettuce leaves. Set both aside until Step 5.
Cut the bacon strips in half and place them in the medium sauté pan. Begin cooking on medium heat, flipping the strips over after 2–3 minutes.
Remove the chicken breasts from the packet and pat dry. Carefully place the chicken breast in the pan next to the bacon. Cook each side for 3–5 minutes. For food safety, poultry should be cooked to an internal temperature of 165ºF.
As the bacon and chicken cook, slice the brioche rolls and place them in the toaster to crisp. Wash the celery sticks, then cut into small, diced pieces. Cut the potatoes into 1/2-inch chunks. In the medium bowl, mix the celery, potatoes, and potato salad dressing. Add salt and pepper as desired. Turn off all heating elements.
To assemble the sandwich: Spread the Dijon mayo onto the top and bottom of each roll. Place the lettuce leaf and sliced tomato on the bottom piece of the roll (add salt and pepper as desired). Follow with the cooked chicken breast, bacon strips, and the top of the roll. Serve the potato salad on the side.