Heat the 8 cups water in a large pot on the stove over medium-high heat. Add the 6 boneless skinless chicken thighs,1 medium onion,1 jalapeño pepper,4 cloves garlic, 2 teaspoons salt, and 1 teaspoon pepper to the water. Bring to a boil, reduce the heat to medium-low, cover, and gently boil for 20 minutes.
Remove 1 cup of the broth and pour it into a blender. Use a small strainer to remove the onion, jalapeño, and garlic from the water then add them to the blender. Add 1 teaspoon chicken bouillon powder, 1 teaspoon oregano, and 3 Roma tomatoes. Blend the vegetables until smooth.
Take the chicken from the pot and shred it using two forks.
Return the shredded chicken to the pot along with the vegetable puree, 3 medium chopped carrots, 3 ribs chopped celery, 3 ears corn, and 2 large chopped russet potatoes. Cover and gently boil until the vegetables are tender, about 10-15 minutes.
Serve the soup fresh with toppings like cilantro, lime, hot sauce, or Mexican Rice.