Heat olive oil in a large stock pot. Add onion and saute for 5-8 minutes until soft and translucent.
Add diced garlic and saute for 30 seconds. Add salt, ginger, turmeric, and chillies and stir to incorporate.
Add sweet potatoes, apple, and carrots and mix well. Add chicken/vegetable broth and bring to a boil.
Cover and simmer on low heat for 25-30 minutes until sweet potato is tender and soft.
Allow soup to cool completely and puree using an immersion blender or a kitchen blender until smooth. Add more chicken/vegetable broth for a thinner consistency. Pour back into stock pot and warm soup on medium heat.
In the meantime, heat a small pan on high heat, place chopped bacon/ pancetta (if using) and cook until crisp. Transfer to a paper towel to drain excess oil.
Ladle soup into serving bowls. If desired, drizzle with Greek yogurt and top with crispy bacon/ pancetta, fresh parsley and/or pumpkin seeds.