Make the dressing: In a food processor, blend together avocado, Greek yogurt, sour cream, cilantro leaves, garlic powder, onion powder, kosher salt and lime juice. Slowly stream in water to thin the dressing out a bit. Transfer to an airtight container and refrigerate until ready to top salads.
For the turkey: Heat a medium saute pan over medium heat and add olive oil. Add ground turkey, stirring to break up the meat with a wooden spoon, until the turkey is no longer pink, about 4-5 minutes. Stir in the taco seasoning and water. Cook for an additional 3-4 minutes, or until most of the water has been absorbed. Set aside until ready to top on salad.
Assemble salad: In a large bowl, mix together romaine lettuce, shredded cheddar cheese, grape tomatoes, avocado, cilantro, red onion, black beans, and tortilla chips. Mix together salad with ¼ cup of dressing or serve on the side. Top salads with ground turkey, jalapeno, and sour cream, if desired, before serving.