Roasted Mushroom Soup with Rye Croutons

Brown them first, then add the stock

Mushrooms are mostly made up of water. In a hot oven, that moisture evaporates as the edges brown and the flavour becomes more concentrated. That matters here: if you cook the mushrooms straight away in stock, they’ll become tender, but won’t develop as much of that roasted, savoury flavour. Use two baking trays if the mushrooms would otherwise overlap; on a crowded tray, they’re more likely to steam than brown. Chestnut mushrooms stay firm and earthy, while oyster mushrooms are a little softer and more fibrous. Together, they give the soup more variety in flavour and texture.

The onion makes a mellow base, and the stock brings everything together without overpowering the mushrooms. After cooking, you only purée part of the soup. This lightly thickens the broth while leaving some recognisable pieces behind. A stick blender works well for this: first lift some of the mushrooms out of the pan with a slotted spoon, purée the rest, then stir the reserved mushrooms back in. If you prefer a smooth soup, purée it all. A splash of cream rounds out the flavour, but isn’t needed for the texture.

Rye bread has a distinctive, slightly sour flavour that goes well with earthy mushrooms. Cut it into small cubes and fry them in a frying pan until crisp; then leave them to cool on a plate so they keep their bite. Stale bread is handy here because it contains less moisture and crisps up more quickly. No rye bread to hand? A sturdy sourdough works too, though the croutons will have a milder flavour. Sprinkle them over the soup just before serving, or they’ll absorb moisture.

Thyme adds a herby, woody note that complements the roasted flavour. Use the leaves in the pan and set a few small sprigs or leaves aside for the top. A modest drizzle of good olive oil adds aroma; more isn’t necessarily better, as the soup shouldn’t be greasy. Taste before serving and add salt and pepper if needed. The stock may already be salty, so wait until the flavours have come together before adding extra salt.

Serve the soup as a starter in small bowls, or pour slightly larger portions for a light lunch with a green salad. The soup can be made ahead and, once cooled, covered and stored in the fridge; reheat it gently until piping hot throughout. Keep the croutons separate and add them at the table. For the best texture, serve the soup hot and the croutons still crisp.