Prep the vegetables. Peel the cucumbers and cut them into slices. Cut the red onion into thin julienne strips and place in a bowl of water to mellow its sharpness while you chop the rest.
Chop the dill and lettuce. Finely chop one tablespoon of dill (optional, you can swap it for cilantro). Slice the lettuce thinly and rinse it. A salad spinner helps dry it well; the drier it is, the longer it lasts in the fridge without oxidizing.
Dice the avocado. Cut half an avocado into small cubes.
Season the chicken. Coat the chicken breasts with lime juice and add salt and pepper.
Cook the chicken. Apply a little vegetable oil spray to your pan. Cook the breasts over medium heat for about 7 minutes, flip them, and cook another 3 to 4 minutes, or until the center is fully cooked.
Make the dressing. Mix the Greek yogurt, olive oil, lime juice, dill, garlic, vinegar, and salt thoroughly. It turns out creamy and delicious, much like ranch but lighter.
Assemble the salad. Combine all the vegetables in a bowl. Serve with the chicken on top and drizzle with the dressing.