Begin by preparing the chicken stock base. In a large pot, bring the chicken stock to a boil over medium heat. Add the chicken breasts, scallions, and garlic. Lower the heat to a simmer, cover, and cook for 20–25 minutes, or until the chicken is fully cooked and tender. Remove the chicken and set aside to cool. Reserve the stock in the pot for the next step.
While the chicken cools, add the sliced yellow potatoes to the stock. These will break down during cooking, thickening the soup naturally. Cook for 10 minutes over medium heat, stirring occasionally to prevent sticking.
Add the white and Andean (or russet) potatoes, along with the corn segments, to the pot. Stir gently and continue simmering for another 20 minutes. Ensure the soup is simmering, not boiling, for even cooking. Season with salt and pepper to taste.
Shred the cooled chicken breasts into bite sized pieces. Return the shredded chicken to the pot, stirring it into the soup gently. Add the guascas to infuse the broth with its distinct herbal flavour. Let the soup simmer for another 10 minutes.
While the soup simmers, prepare the garnishes. Slice the avocado, chop the cilantro, and arrange the capers and heavy cream in small serving bowls. If desired, prepare steamed white rice as a side dish.
Taste the soup and adjust the seasoning as needed. The broth should be hearty and flavourful, with a thick consistency from the yellow potatoes. If the soup is too thick, add a splash of water or stock to reach your desired consistency.
Once the potatoes are tender and the flavours melded, remove the pot from heat. Allow the soup to rest for 5 minutes before serving to enhance the depth of flavour.
Serve the Ajiaco hot in individual bowls. Top each serving with a drizzle of heavy cream, a sprinkle of chopped cilantro, and a spoonful of capers. Add slices of avocado on the side. Offer steamed rice for those who prefer a heartier meal. Pair with fresh bread and enjoy with a refreshing drink, such as a light lemonade or a Colombian aguardiente for a festive touch.