Warm the olive oil in a large pot over medium heat.
Sauté onion and jalapeño until softened and lightly golden, 4–5 minutes.
Stir in garlic, cumin, oregano, and coriander. Cook until fragrant, about 30 seconds.
Add the rinsed rice and stir to coat, toasting briefly for 1 minute.
Pour in the chicken broth and the diced tomatoes with their juices. Bring to a boil.
Reduce heat and simmer gently for 15 minutes, stirring occasionally so rice doesn’t stick.
Stir in the shredded chicken and cook until rice is tender, 8–10 minutes more.
Off heat, stir in lime juice, lime zest, and cilantro. Season with salt and pepper.
Ladle into bowls and top with crushed tortilla chips and avocado, if using. Serve right away.