Roasting carrot until lightly caramelized will make this carrot ginger soup stand out. If you wish add a swirl of coconut milk or heavy cream while serving if you wish.
Heat butter in a heavy-bottom pot. Add diced onion and saute until softened. Add diced carrot and potatoes. Cook on medium heat for 7-8 minutes until you see the edges are caramelized. Keep string to prevent the veggies from burning.
Add grated ginger, ground cumin, salt and pepper. Mix everything well and cook for another 2 minutes for the spices to develop flaovr.
Add half of the stock ( just enough to cover the veggies). Adding warm stock quickens the cooking process. Add thyme sprig, cover, and cook until veggies are cooked tender and really soft.
Once cooked, remove the lid, fish out the thyme sprigs. Using a hand blender blend the soup until smooth right in the cooking vessel. (or you can also transfer the veggies to a blender along with a little cooking liquid and blend it until smooth. Be very careful as the hot liquid might splash)
After blending, add more warm stock to get the preferred consistency. Check the seasoning and adjust.
To make garlic croutons
While the vegetables are getting, preheat the oven and make some garlic croutons.
Notes
Begin with 1 teaspoon of ground cumin and grated ginger. if you prefer stronger flavor, then add up to 1.5 teaspoons of each. I usually go with 1 teaspoon as I don't want the rest of the flavors to overpower the delicate carrot flavor.