Start by roasting the poblanos. I like to put the peppers directly over the flame of the gas burners, rotating the peppers until all of the skin is charred. Then I place the peppers in a covered bowl for 15 minutes. This lets the peppers sweat off the skin a bit, and gives them time to cool. After 15 minutes peel off the skin, and loosely chop the peppers. I recommend discarding the seeds, unless you want an extremely spicy soup.

Next, melt the butter in a saucepan over medium heat. Then add the garlic and onions. Cook until the onions are translucent. Then add ¾ cup chicken broth and heavy cream. Bring to a boil, add the poblanos, and let boil and reduce for 6 minutes.

Slice the avocados in half, remove the pits, and scoop them out into a blender. Then add the poblano mixture and liquify. Then add the salt, pepper, and cumin, sour cream, and remaining chicken broth. Blend to combine. Add more sour cream and salt to taste.