Puree the soup using an immersion blender or traditional blender until it is very smooth. Return soup to pot and season to taste with salt. I measured how much salt I put in so I could tell you guys, but then I promptly forgot how much I used. ½ a teaspoon sounds like a good starting place though.
While the tomatoes are cooking, dice or crumble the queso fresco, prep your cooked chicken, and dice your avocado.
Tip: Queso fresco is easy to find at your local grocery store. Look for it in the cheese section.