Place oil in a soup pot over medium heat and cook the onions and carrot, stirring occasionally, until the onions soften, about 5 to 8 minutes. Do not let the onions or carrots brown. Sprinkle a teaspoon of salt over the carrots and onions as they cook.
Add stock and water, ginger, and strips of orange zest. Bring to a simmer, cover, and cook until the carrots soften, about 20 minutes. Remove the strips of orange zest and discard.
Using an emersion blender (or regular blender) purée until completely smooth. If using a regular blender, fill the blender bowl a third full with the hot liquid and keep one hand pressing down on the cap of the blender to keep it from popping off.