Using a large dutch oven or stock pot over medium heat, cook the chicken breasts with a small amount of oil. Browning the outside of the chicken will help enhance the flavor. As a faster option, I use the breasts from an already roasted chicken which gives the soup a richer roasted and smoky flavor. Even when I use the roasted chicken, I still cook it again in the pot to help it pull apart easier.
Remove the chicken placing it into a bowl and shred into small bite size chunks and set aside. You can move on to the next few steps to let the chicken cool down before shredding!
Add the diced onion, garlic and a small amount of oil to the pot and cook until soft - about 2 minutes.
Add the remaining ingredients (except chicken), and bring to a gentle boil for about 2 mins. Reduce temperature to simmer.
Add the shredded chicken, cover the pot and allow to simmer for 25 minutes or more stirring occasionally.
Salt... About half way through the simmering time, taste the soup and add salt as needed. The reason I do it this way is because I use roasted chicken which typically has been brined and is quite salty and the chicken broth has salt in it as well. I generally don't have to add much more, but the saltiness of the soup is a personal preference so adjust as desired.
Garnishes: Add as many or few as you like. Personally I like them all and I double up on the avocado! Fun serving tip - Place garnishes in small bowls and allow everyone to chose their own!