In a large pot, heat 2–3 tablespoons of vegetable stock over medium heat. Add the sliced leeks and sauté for about 5 minutes until tender and wilted.

Stir in the crushed garlic and cook for an additional 30 seconds until fragrant.

Add the chopped potatoes, rolled oats, and remaining vegetable stock to the pot. Season with black pepper and salt, then stir to combine.

Increase the heat to bring the mixture to a gentle boil for about 5 minutes.

Reduce the heat and let the soup simmer uncovered for about 20 minutes, stirring occasionally until potatoes are tender.

Use an immersion blender to puree the soup until smooth or transfer in batches to a standard blender.

Adjust seasoning with additional salt or black pepper to taste.

Ladle the soup into bowls and garnish with chopped chives before serving.