Step 1
To a large pot over medium heat, add the oil. When it’s hot and shimmering, add the scallions, thyme, garlic, and onion and cook, stirring frequently, until soft, about 7 minutes. Stir in the callaloo, stock, and halved chile, bring to a simmer, and cook, stirring occasionally, until the callaloo is tender, about 10 minutes.
Step 2
Transfer the soup to a blender, discard the chile, and blend until smooth. Return the soup to the pot over medium heat, add the yam, and cook, stirring frequently, until the yam is tender, about 15 minutes. Season to taste with salt and black pepper, then divide the soup among bowls and serve with the finely chopped chiles on the side.