First, make the dressing. In a small bowl, combine the Greek yogurt, milk, lemon juice, chives, dill, garlic powder, onion powder, parsley, salt, and pepper. Whisk until smooth. Set aside.
Place the bacon strips in a large cast-iron or nonstick skillet and heat over medium heat. Turn the strips as needed until they reach the desired crispness, 8 to 12 minutes. Drain well on a paper-towel-lined plate.
Place the chopped lettuce in a large bowl. Add the tomatoes, avocado, croutons, and onion. Chop the cooked bacon strips and add them to the salad. Drizzle with dressing and serve immediately.