Sour Soup with Lettuce

Bring the 2 quarts of water to a boil in a large pot over high heat.

Peel and slice the carrot, parsley root, and onion into thin rounds or batons, then add them to the boiling water.

Peel and mince the garlic clove if using, and add it to the pot. Reduce heat to medium and simmer for 10–12 minutes until the vegetables begin to soften.

While the vegetables cook, wash the Boston lettuces thoroughly and remove the outer leaves if wilted, then chop the firm cores and tender leaves into bite-sized pieces.

Add the chopped lettuce to the pot and stir to combine. Simmer for 5–7 minutes until the lettuce is tender.

In a small bowl, whisk together the flour with 2–3 tablespoons of the hot broth until a smooth paste forms, then slowly pour it into the pot while stirring constantly to avoid lumps.

Continue simmering for 3–4 minutes until the broth thickens slightly.

In a separate small bowl, whisk together the egg yolks and sour cream until smooth and pale.

Remove the pot from heat and allow to cool for 1–2 minutes, then slowly ladle some hot broth into the yolk mixture while whisking constantly to temper the eggs without scrambling them.

Slowly pour the tempered yolk mixture back into the pot while stirring gently and continuously to create a creamy consistency.

Stir in 2–3 tablespoons of vinegar to taste, then season with salt to balance the sourness and broth flavors.

Ladle the soup into bowls and garnish generously with fresh chopped parsley before serving.