Mash the sardine in a small bowl or mason jar. Add all dressing ingredients. Stir/shake like crazy.
Refrigerate for at least 15 minutes to 1 hour for the flavors to blend.
Meanwhile, add the chopped lettuce into a large bowl, season with some salt, black pepper, and a drizzle of lemon or lime juice. Massage the leaves well for 3-5 minutes.
Drizzle with olive oil and let stand like his for at least 30 minutes.
This step helps the lettuce to soak up the flavors that will soften it and reduce the bitterness quite a bit (I don't recommend using a very bitter Olive oil here).
Chicken. Mix the chicken seasonings in a small bowl and rub the chicken breast on both sides.
Heat up cooking oil in a nonstick skillet over medium-high heat. Once the oil is sizzling hot, add the chicken breast and cook for 5-6 minutes on both sides (small to medium chicken breast). For a small or thinner chicken breast you’d need about 3-4 minutes on both sides. To ensure that chicken is cooked through, use a kitchen thermometer inserted into the thickest part of the chicken to register 165 Degrees Fahrenheit. Set aside on a plate lined with kitchen paper towels.
Assemble. Arrange the lettuce in a large serving bowl, follow with chicken, tomatoes, eggs, gluten-free croutons, Parmesan cheese, lime and lemon slices and fresh black pepper. When the dressing is refrigerated enough, give it a good stir and pour over the salad. Dig in!