In heavy bottomed pot, heat fat over medium-high heat. Add chopped onion, leek, bell pepper, carrot, and medium-heat chile pepper. Sprinkle with a little salt, sauté, and allow vegetables to become soft. About 5 minutes.
Add grated garlic (it helps to grate with a microplane), cumin, and oregano. Sautee until very fragrant, about 2 minutes.
Add 4 cups warmed chicken broth. Stir, then add in potatoes, corn and chicken.*
While starches/chicken are cooking, blend the following in a blender: 1 bunch of cilantro, 1 hot chile pepper, 1 medium clove of garlic, and 2 cups warmed chicken broth. Once blended, add mixture to soup pot.
Once everything is cooked through, taste and add salt and pepper. Taste again and adjust as needed.
Serve with limes and garnish with chopped scallions.