Add the diced onion, carrot and celery. Cook, stirring occasionally, until the vegetables are softened and the onion is translucent, about 7–9 minutes.

Add minced garlic and cook 30–45 seconds until fragrant, taking care not to let it brown.

Sprinkle the flour over the vegetables and stir constantly for 1–2 minutes to cook the raw flour taste and create a light roux.

Gradually pour in the chicken or vegetable stock while stirring to combine and prevent lumps. Add the water, diced potato (if using), bay leaf and thyme sprigs.

Bring the soup to a gentle simmer. Reduce heat to low, cover partially, and simmer until potatoes are tender and flavors meld, about 20–25 minutes.

Remove the bay leaf and thyme stems. If you want a smooth texture, use an immersion blender to purée the soup directly in the pot until desired consistency, or transfer in batches to a blender and purée, then return to pot. For a chunkier soup, skip blending.

Stir in heavy cream or milk if using. Warm through but do not boil once dairy is added, about 3 minutes. Taste and adjust seasoning with salt and pepper.

Finishes & garnish

Remove from heat and stir in chopped parsley and most of the chives, reserving a pinch for garnish.

Ladle soup into warmed bowls and garnish with remaining chives and a small drizzle (optional) of olive oil or a pat of butter.

Bread & butter

Preheat oven to 400°F (200°C). Slice the baguette on a diagonal into 1/2-inch thick slices.

Lightly brush each slice with olive oil if using, and place on a baking sheet. Toast in the oven until golden and crisp at the edges, about 6–8 minutes.

Spread softened butter on the warm toasted bread and sprinkle a very small pinch of sea salt flakes if desired. Serve alongside the soup.