Add the shallot, cilantro, garlic, red pepper flakes, olive oil, red wine vinegar, salt, and black pepper to a food processor. Blend until smooth to make the cilantro vinaigrette.
Heat the olive oil in a large skillet over medium-high heat.
Add the diced onion and cook for about 5 minutes until softened.
Stir in the garlic and cook for another 30 seconds.
Add the ground chicken and cook for 6–7 minutes, breaking it apart as it browns.
Stir in the taco seasoning and water. Reduce the heat and simmer for about 5 minutes.
In a large serving bowl, add half of the shredded romaine lettuce.
Layer half of the tomatoes, corn, black beans, cheese, avocado, scallions, cilantro, and red onion over the lettuce.
Repeat with the remaining lettuce and toppings.
Spoon the warm seasoned chicken over the salad.
Drizzle the Chicken Taco Salad with the cilantro vinaigrette and gently toss before serving.