In a large heavy-bottomed pot, heat the ghee over medium heat.
When the ghee is hot, add the onion, garlic, salt, and garlic powder and stir to combine.
Cook, stirring often, until the onion is softened, about 8 minutes.
Add the tomatoes, roasted peppers, and broth and bring to a boil.
Turn the heat down to medium-low, cover, and simmer for 10 minutes.
Add the cilantro, then puree the soup in batches in a blender or with an immersion blender.
Season to taste with pepper and more salt, if needed.
Serve with lime wedges, if desired.