Season the chicken breasts evenly on both sides with smoked paprika, garlic powder, salt, and black pepper.
Heat olive oil in a heavy skillet over medium-high heat. Cook the chicken for 6 to 7 minutes per side until the internal temperature reaches 165°F (74°C).
Place one slice of provolone cheese over each chicken breast during the final minute of cooking, covering the pan briefly to melt the cheese.
In a separate pan, cook the bacon over medium heat until crispy, then drain on paper towels.
In a small bowl, mash the avocado with lime juice and a pinch of salt until creamy but slightly chunky.
Lightly toast the sourdough bread slices until golden brown.
Spread 1/2 tablespoon of garlic aioli on each slice of toasted bread.
To assemble, place arugula and tomato slices on the bottom bread slices. Top with the cheesy chicken breast, two slices of bacon, and red onion.
Spread a generous layer of the mashed avocado on the top bread slices and close the sandwiches.