In a large saucepan, heat 2 tablespoons olive oil over medium-high heat until shimmering. Add onion, celery, and carrots. Cook, stirring occasionally, until the vegetables have softened and the onion has started to brown, about 10 minutes.
Add the garlic and stir until fragrant, about 30 seconds. Stir in the broth, tomatoes and juice, jalapeño, cumin, and coriander.
Bring to a boil; reduce heat and simmer, uncovered, for 20 minutes. Stir in chicken and cilantro (if using). Season to taste (I like 1 teaspoon salt and 1/2 teaspoon pepper). Serve, offering avocado, cheese, sour cream, and tortilla chips on the side.