Use a medium-sized pan to heat olive oil over medium-high heat.
Once the oil is ready, add onion and garlic and cook until the onions have slightly softened.
Add the carrots, celeriac, stock, chili flakes, salt, and pepper. Mix.
Cover the pan with a lid, then bring to a boil.
Adjust the heat to medium-low and continue simmering until the vegetables are cooked.
Take the saucepan off the heat, then use an immersion blender to puree the soup.
Once you get a smooth texture, add the yogurt, mix, then taste and adjust seasoning.
Place the saucepan back on the heat, covered, then bring to a boil.
Turn the heat off, then transfer soup into bowls for serving.
Serve your Turkish celeriac soup wiith garlic and mint sauce --- and more fresh dill, if desired.