To a large bowl, or resealable bag, add 1/3 cup lemon and dijon mustard dressing, chicken breast, salt and pepper. Toss to coat well. Marinate for 1-2 hours in the refrigerator.
While the chicken marinates, cook the bacon according to package directions. Once done, allow to cool and roughly chop. Set aside.
To a grill plan or skillet, add 1 tbsp oil over medium high heat. Once hot, add chicken breast, grill for about 6-8 minutes, and flip, cooking for 4-5 more minutes, depending on thickness (should be 165℉). Remove chicken from pan and allow to rest 5 minutes. Chop and set aside.
Divide lettuce between four plates then top with chopped bacon, tomatoes, chopped avocado, and chicken. Serve with additional Dijon Vinaigrette and toss to combine