Peel off the outer layers of the lemongrass and chop off most of the top and a small portion of the bottom. Cut into long strips, then mince finely. Take care with this step; otherwise the lemongrass will have the texture of wood splinters.
Heat the sesame oil in a medium skillet and sear the chicken breast on both sides. Remove it to a separate dish.
Cook the lemongrass, ginger, garlic, and red chili in the pan for about one minute over medium-low heat. Add the vinegar, lime juice, soy sauce, honey, and water and return the chicken breast to the pan. Cover and cook for about 10 minutes, or until it is cooked through. Allow the chicken to cool slightly, then slice.
To serve, divide the romaine lettuce and cilantro between two bowls. Top with pear slices and chicken. Season the remaining liquid in the pan to taste with sea salt, then drizzle over the salads.