Heat 1 tsp olive oil in a pot over medium-high. Add 1 diced small onion and 2 minced garlic cloves. Cook until onion softens, 2 to 3 min. Stir in 2 tsp tomato paste and 1 tsp chili powder. Cook 1 min. Pour in a 900-mL carton no-salt chicken broth and 1/4 tsp salt. Add 2 boneless, skinless chicken breasts. Boil, covered, until chicken is cooked through, 6 to 8 min. Transfer chicken to a cutting board to cool slightly. Add 2 cups canned tomatoes, chopped, 2 cups frozen corn and 2 to 3 tbsp finely diced pickled jalapenos to soup. Reduce heat to medium. Gently boil 5 min. Using 2 forks, shred chicken, then stir into soup. Ladle into 4 bowls and top with 1 chopped avocado and 1/2 cup chopped cilantro.