Heat olive oil in a large pot over medium heat. Add the onion, garlic, and jalapeno. Cook for 3 minutes until the onion softens.
Stir in chili powder, cumin, and oregano. Cook for 1 minute until fragrant.
Add the chicken breasts, chicken broth, and diced tomatoes. Bring to a simmer. Cover and cook for 20 minutes until the chicken reaches 165°F.
Remove the chicken and shred it with two forks. Return the shredded chicken to the pot. Season with salt and pepper.
Ladle the soup into bowls. Top each serving with sliced avocado, a squeeze of lime juice, and chopped cilantro.