Add olive oil to a hot 10-inch crock or Cast Iron Dutch oven over coals. Set on a grill rack for more stability.
Add tomatoes, onion, garlic, and jalapeno with a pinch of salt. Sauté for 15 minutes, stirring occasionally.
Add the chicken and sauté briefly before stirring in the chicken stock, thyme, oregano, and 1 tsp of salt. Scrape up the bits on the bottom of the pan and bring everything to a simmer.
Simmer for 20 minutes or until the chicken is cooked through. Carefully shred or break up the chicken.
Taste the soup and adjust the seasonings to your liking. Garnish the pot of soup with chopped onion, cilantro, avocado, tortilla chips, and lime juice.