Heat the oil in a medium pot over medium-high heat. Add the onions, ginger, cumin and salt and pepper to taste. Cook until the onions have softened slightly, about 2 minutes. Add the garlic and cook an additional 1 minute. Add the carrots, vegetable stock and 1 cup water. Cover, bring to a boil and reduce to a simmer. Cook until the carrots are tender, about 30 minutes. Add the coconut milk.
Blend in batches until smooth, or use an immersion blender. Garnish with a dollop of yogurt and chopped parsley if desired.
When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.