- Preheat oven to 275ºF and place a cookie rack over a large baking sheet. Add sliced sweet potatoes to a medium mixing bowl and drizzle with olive oil. Toss to coat. Spread on cookie rack leaving space in between for air to flow. Bake for 30 minutes.
- Brush sweet potatoes with Takumi sauce and return to oven for 15-20 minutes longer. Cool at room temperature while preparing soup.
- Increase oven temperature to 400ºF and line a large baking sheet with parchment paper. Spread cubed sweet potatoes on baking sheet and drizzle with one tablespoon of olive oil. Toss to coat. Roast for 25 minutes, until tender and browned around edges.
- While sweet potatoes roast, heat remaining tablespoon of olive oil over medium heat in a large pot and add celery and onion. Sauté for 5 minutes. Add garlic and ginger and sauté 5 minutes longer, stirring regularly.
- Add bay leaf, salt, pepper and vegetable stock to pot and bring to a boil. Simmer for 10 minutes. Remove bay leaf.
- Ladle soup into a high-speed blender or use an immersion blender and add roasted sweet potatoes and coconut milk. Blend until smooth.
- Ladle soup into bowls and serve hot topped with teriyaki sweet potato chips and fresh parsley.