Prepare to cook the quartered chicken by placing it in a large stock pot with the water. Add the oregano, red onion, celery, garlic cloves, basil, and bay leaf. Cook chicken over medium heat for approximately 1 1/2 hours, or until the meat is tender.
Allow chicken to cool, then remove the meat from the bones, chopping or shredding it as you go. Reserve the cooked chicken for use later. The broth from cooking the chicken may be frozen and reserved for future use in soups and stews.
Place shortening, sliced white onion, and minced garlic clove in a large skillet and sauté the mixture over medium heat until onion is tender. Add the chopped and shredded chicken, tomato, jalapeño peppers, cinnamon, salt, and peppers to the bubbling skillet. Reduce the heat to simmer over a low-heat setting for about 10 to 15 minutes.
Warm the tortillas as directed on the manufacturer's packaging, because they are easier to fill when slightly warmed. Place about 1/2 cup of the chicken mixture horizontally across the bottom half of each tortilla. Do not extend the mixture beyond 1 1/2 inches at the sides and bottom. Fold the sides in over the filling and roll the tortilla as you would a jelly-roll. Secure each rolled tortilla with a toothpick.
Heat 2 inches of shortening in a heavy skillet over medium-high heat. Fry each rolled tortilla in hot shortening until crisp and lightly browned. Drain on absorbent towels and keep warm under a tent of foil while frying the remaining tortillas.
Assemble the Chimichangas by placing each rolled tortilla on a plate and garnishing it with about 1/4 cup of sour cream, a few tablespoons of guacamole, a small handful of shredded cheddar cheese, lettuce, and tomato wedges.