Colombian Chicken and Potato Soup

Name: Colombian Chicken and Potato Soup
Cuisine: American, Latin American
Ingredients: 4 cups chicken stock; 2 chicken breasts (bone in, skin on preferred); 3 medium yellow potatoes, peeled and sliced; 3 medium white potatoes, peeled and sliced; 3 medium Andean potatoes (or russet as a substitute), peeled and sliced; 3 ears of corn, cut into 2-inch segments; 2 scallions, chopped; 2 cloves garlic, minced; 1 small bunch guascas (or 1 tsp dried guascas, available in Latin stores); Salt and pepper to taste; 1/2 cup heavy cream; 1/2 cup capers; 1 ripe avocado, sliced; Fresh cilantro, finely chopped; Steamed white rice (optional)