Step 1

Using metal tongs, toast the chiles carefully over an open flame (using a gas burner–or alternatively, in a dry cast-iron skillet over medium heat) until they are pliable, slightly blistered, and very fragrant. Set aside on a cutting board to cool. Cut in half, and scrape out and discard the seeds and stems. Cut the chilis into small pieces and place in a high-powered blender (such as a Vitamix) along with the canned fire-roasted tomatoes and their juices. Set aside for later.

Step 2

Heat the olive oil in a large soup pot over medium-low heat. Add the chopped onion and a large sprinkle of kosher salt. Sauté for 8 to 10 minutes, stirring frequently, or until the onions are soft and translucent. Add the chopped garlic and sauté for an additional 30 seconds to 1 minute, stirring continuously, until fragrant. Remove from the heat.

Step 3

Transfer the cooked onion and garlic mixture to the blender with the chilis and fire-roasted tomatoes. Puree the ingredients together, scraping down the blender if necessary, until the chilis have been fully integrated and the mixture is completely smooth and dark orange-red in color.

Step 4

Return the empty soup pot to high heat. Once the pot is very hot, add the pureed tomato chili mixture all at once–it should sizzle immediately when it hits the pan. Continue to cook over high heat for about 4 to 5 minutes, stirring constantly with a spatula, until the mixture thickens and concentrates substantially. It will splutter and bubble a bit. Once ready, the mixture should be slightly darker in color and resemble the thickness of a loose tomato paste.

Step 5

Add the chicken broth to the pot and combine thoroughly using a spoon or whisk. Bring the mixture to a boil. Reduce the heat to low and allow the broth to lightly simmer, uncovered, for 20 minutes, stirring occasionally. Season the broth with salt and pepper. If the broth tastes at all flat, you most likely haven't added enough salt.

Step 6

Over low heat, add the greens and stir until fully incorporated. Allow the greens to cook at a low simmer (baby kale will take just a minute or two; collards or curly kale may take 5 to 7 minutes total), until they are very tender. Add the chicken and stir to distribute. Cook for an additional 2 to 3 minutes over very low heat, stirring once or twice, until the chicken has just cooked through (this will not take long, so watch the pot carefully to avoid overcooking it). Just before serving, add the juice of half a lime. Taste once again, seasoning with additional salt and pepper if necessary.

Step 7

Serve hot and garnish with toppings (or alternatively, place desired toppings in the empty soup bowls and ladle the soup directly over them).