For the chicken: Place the chicken in a shallow dish just large enough to hold them. Whisk the oil, lemon zest, lemon juice and garlic in a small bowl until combined. Pour the oil mixture over the chicken and toss to coat. Cover the dish with plastic wrap and refrigerate, at least 4 hours and up to overnight.
Preheat a grill pan or an outdoor grill to medium-high heat. Remove the chicken from the oil mixture and pat dry. Sprinkle with salt and pepper and grill the chicken until golden brown and cooked through, about 12 minutes per side. Transfer the chicken to a plate to cool slightly. Thinly slice the chicken against the grain and set aside.
For the dressing: Mix the sour cream, Parmesan, lemon juice, mustard, Worcestershire, anchovy, garlic and season with salt and pepper in a medium bowl.
For the sandwich build: Place the sliced chicken, 1/2 cup sour cream Caesar dressing, tomatoes, romaine and Parmesan Croutons in a large bowl. Toss to coat evenly. Fill each tortilla with the chicken mixture.
To make croutons:
Preheat the oven to 375 degrees F. Add the bread and Parmesan to a large bowl and sprinkle with salt and pepper. Drizzle with the oil and mix well. Spread the mixture onto a baking sheet and bake until light golden brown, about 15 minutes.