Place chicken thighs between two sheets of parchment paper and pound lightly to ensure even thickness.
Season both sides of the chicken with salt and black pepper.
Heat olive oil in a large cast-iron skillet over medium-high heat until the oil begins to shimmer.
Place chicken thighs in the skillet and immediately apply heavy pressure using a cast-iron meat press or a second heavy skillet to maximize surface contact.
Sear for 5 minutes until the edges are deeply browned and crispy; flip and repeat for another 4 minutes or until internal temperature reaches 165°F (74°C).
Remove chicken from the skillet and slice into 1/2-inch strips.
In a mixing bowl, toss the shredded romaine with the Caesar dressing and 2 tablespoons of the Parmesan cheese.
Toast tortillas over an open gas flame or in a dry pan for 30 seconds per side until lightly charred and pliable.
Distribute the sliced chicken evenly among the tortillas, then top with the Caesar salad mixture.
Garnish with the remaining Parmesan cheese, crushed croutons, and serve with lemon wedges.