Trim your chicken breasts of any fat.
Add the chicken, spinach-basil pesto, all-purpose seasoning, and dijon mustard to a large bowl or Ziploc bag. Mix everything around until the chicken is completely covered in pesto and seasonings; marinate (covered) in the refrigerator for at least 1 hour.
While the chicken is marinating, chop your greens and wash/dry them using a salad spinner. Season them with a bit of salt and black pepper if preferred.
Slice grape tomatoes in half, and season with a pinch of salt.
Slice the red onion into rings or chop them into small cuts. I store all veggies (lettuce/spinach, tomatoes, and onion) in the fridge in separate containers until the proteins are ready. Cook your marinated chicken in a skillet or air fryer until fully cooked. Remove from heat and let the chicken rest for at least 3 minutes before slicing into it.
In a bowl, assemble your salad with the lettuce mix, pesto chicken, tomatoes, and onions. Slice half of an avocado for each bowl and add to the salad. Top with the feta cheese.
Either toss with your favorite dressing or leave it on the side. I made a tasty pesto vinaigrette for this because I can't get enough of the pesto flavor! Simply blend together more spinach-basil pesto, a touch of extra-virgin olive oil, and some extra lemon juice until it is a thin consistency and drizzle over your salad. Serve immediately. Enjoy!