Place the peppers on the top rack of your oven. Broil the peppers until the skin is charred, approximately 5 minutes.
Flip the peppers and char the second side. When both sides are charred, remove them from the oven and place them in a sealed plastic bag (such as the one you got them in from the grocery store) or a sealed tupperware container. Let them sit for at least 5 minutes as the steam will make it easier to remove the skins.
Peel the skin off of the peppers. You do not need to remove all of it, but get most off. Remove the stems and seeds.
Roughly chop the peppers and place in a food processor or blender. Add the lime juice and salt. Process until the peppers are blended to your preferred consistency. Add the sour cream and blend briefly again to combine.