In the slow cooker or large pot, combine the chicken, chopped onions, minced garlic, chicken broth, diced tomatoes, chili powder, cumin, paprika, dried oregano, salt, and pepper.
Cover and cook on low heat for 6-8 hours or on high heat for 3-4 hours, until the chicken is tender and easy to shred.
Once the chicken is fully cooked, use two forks to shred the meat in the pot. Mix the shredded chicken with the flavorful sauce and let it simmer for an additional 10-15 minutes on low heat.
Warm the flour tortillas in a skillet or microwave until pliable.
To make the burritos, lay a tortilla on a clean surface as the base. Add a generous spoonful of Mexican rice, followed by some refried beans, shredded chicken, lettuce, tomatoes, avocado, and cheese.
Fold the sides of the tortilla inwards and then roll it up tightly to create a burrito. You can wrap it in aluminum foil to hold its shape, if desired.
Continue the same procedure with the remaining tortillas and fillings.
Serve the authentic Mexican shredded chicken burritos warm and enjoy!