Place the chicken in a large baking dish. Whisk together the lemon juice, olive oil, garli,c and sea salt and then pour over the chicken. Marinate at room temperature for 1 hour.
Heat grill pan over medium heat for 2 minutes. Grill the chicken until cooked through. You can also grill on an outdoor grill. Cool for 10 minutes and then cut into bite-size pieces.
Place the mayo, olive oil, honey, Dijon, and apple cider vinegar in a blender and blend until smooth. The dressing makes more than needed for just one salad, so store the leftovers in a Mason jar in the fridge. You can use it for other salads or as a dip for vegetables or chicken nuggets.
Place the lettuce, cherry, tomatoes, avocado, cucumber, pumpkin seeds, and chicken in a large salad bowl and dress with the honey-mustard dressing.