Loaded Chicken Taco Salad with Creamy Lime-Cilantro Dressing

I've just started to get into cooking, used to be a chuck it in the microwave or takeaway kinda gal, Made this recipe tonight and OMG amazing! so so yummy! My partner hasn't stopped raving about it!

Ingredients:

2 tablespoons olive oil
1 1/4 pounds boneless skinless chicken breasts, cut into bite-sized pieces
one 1.25-ounce packet taco seasoning, divided (I use reduced sodium, medium heat)
4 cups romaine lettuce
1 or 2 medium tomatoes, diced (I use vine-ripened; Roma or cherry tomatoes may be substituted)
1/2 cup canned corn, drained (fresh or frozen may be substituted)
1/2 cup canned black beans, drained and rinsed
1 medium Hass avocado, peeled and diced
1 cup shredded cheese (I use a monterey Jack and cheddar blend)
1 cup seasoned tortilla chips, crushed (I crush Doritos in my palm)
1/2 cup mayonnaise (lite okay)
1/4 cup sour cream (lite okay, plain Greek yogurt may be substituted)
3 to 4 tablespoons lime juice, or as necessary for flavor and consistency
1/4 cup cilantro leaves, minced
1/2 teaspoon granulated sugar, optional and to taste