Heat a cast iron skillet over high heat. In a small bowl, whisk the avocado oil with the dried herbs. Brush the herbed avocado oil over the chicken breast, coating all sides.
Reduce the skillet heat to medium high, then place the chicken breasts into the skillet. Sear 4-5 minutes; flip and sear on the other side an additional 4-5 minutes, or until an instant read thermometer reads 160°F when inserted into the thickest part of the breast. Remove the chicken from the skillet and set aside to rest while you prepare the remainder of your salad ingredients.
Add the chopped bacon to the skillet and cook until the fat renders and the bacon is crisp. Remove the bacon with a slotted spoon and set aside.
By now, the chicken will be rested enough that you can sliced it against the grain into ½” slices.
In a large salad bowl, toss the romaine lettuce, sundried tomatoes, cucumber, and red onion.
Divide the salad between four plates, then top with ¼ of the of the sliced chicken and ¼ of the cooked bacon. Dress each plate with 2 tbsp of ranch dressing and serve.