1. Heat oil in a six-quart pot. Add onions and sauté until golden. Add garlic toward the end and sauté for an additional minute.
2. Add sweet potatoes and carrots. Sauté three to five minutes, stirring occasionally.
3. Stir in silan, soup mix, salt, pepper, and nutmeg. Add boiling water to cover vegetables, plus a little more.
4. Cover and cook about 30 minutes, or until vegetables are soft. Add thyme stems and cook three to four minutes more.
5. Remove soup from heat. Remove thyme stems and discard (leaves can stay in the soup). Blend until smooth with an immersion blender.