In a large, heavy bottomed pot, add water, chicken, scallions, and garlic. Bring to a boil and cook on high for approximately 20 minutes until chicken is cooked through.
Using tongs, remove chicken from pot and place on a chopping board to cool.
Add potatoes to pot and cook for 10 more minutes.
Meanwhile, remove any remaining skin and fat on chicken thighs. Using two forks, remove meat from bones and shred into small bite-sized pieces. Place in two small serving bowls.
Add carrots, sweet potatoes, guascas, and corn to pot, continuing to cook at a boil so potatoes start to disintegrate and thicken the soup.
Cook approximately 10 more minutes and add salt and pepper to taste.
To serve soup into bowls, add one ear of corn and a mixture of the potatoes so diners can experience a mixture of flavours.
Serve with a side of avocado, capers, cream, and chicken. Invite guests to garnish their soups as they please.