Prepare the chicken: In a small bowl, combine the salt, garlic powder, onion powder, dried oregano, and black pepper.
Sprinkle the seasoning mix on both sides of the chicken breast.
Heat the oil in a large skillet over medium-high heat. Add the chicken breasts, drizzle with 2 teaspoons of soy sauce, and cook for 5 to 6 minutes on each side until cooked through. Transfer the chicken to a cutting board and set aside to rest.
To the same skillet, add the onion, bell pepper, jalapeno, and remaining 2 teaspoons of soy sauce. Cook for 6 to 8 minutes, stirring occasionally, until the onions and peppers are tender and cooked through. Remove the skillet from the heat.
Chop the cooked chicken into small bite-sized chunks and add it back to the skillet with the onions and peppers. Stir to combine and set aside.
Warm up the tortillas: Melt ½ tablespoon of butter in a large skillet over medium-high heat. Add a flour tortilla and cook for about 15 seconds per side. Transfer the tortilla to a plate, cover it with aluminum foil or plastic wrap to keep it warm, and repeat the process with the remaining tortillas.
Assemble: Add a tortilla to the same hot skillet and top with ½ cup of shredded cheese, followed by some of the chicken mixture, and another ½ cup of shredded cheese. Place the second warmed tortilla on top and lightly press down to help the quesadilla keep its shape.
Cook: Cook the quesadilla for 1-2 minutes per side, or until the bottom of the quesadilla is golden-brown, and the cheese has fully melted. Repeat with the remaining tortillas.
Serve: Slice each quesadilla into 4 pieces and serve with salsa, sour cream, and guacamole.