Soupe de Poisson

Like bouillabaisse, soupe de poisson grew out of the Mediterranean fishermen's habit of cooking the small, bony rockfish that could not be sold — but where bouillabaisse keeps the fish to serve, this soup makes a virtue of the very smallest, ungainly fish by cooking and milling them whole, bones and all, into a smooth purée-broth. It is found all along the Provençal and Languedoc coast, from Marseille to Sète, served in homes, fishmongers' stalls and brasseries, and is widely sold ready-made in jars. The garnish of rouille, croûtes and grated cheese is the shared southern table ritual it borrows from bouillabaisse. No single town or cook claims it; it is a regional staple of long but undocumented standing.

A deep rust-orange soup, smooth and almost creamy in body though there is no cream — all of it from milled fish and emulsified oil. The flavour is concentrated sea: shellfish-sweet, savoury, with the warm thread of saffron and fennel running under it and a faint bitterness from the bones. You float a croûte spread with red rouille, shower it with gruyère, and let it sink and melt, the cheese stringing into the soup, the garlic-chilli rouille blooming with heat. Rich, warming and intense. A thin, watery version means the fish were too few or the soup under-reduced.

The body comes from cooking small whole rockfish — heads, bones and all — hard enough to extract their gelatin and break them down, then forcing everything through a food mill or sieve so the bones are pulverised and strained out while their substance stays in the broth. A vigorous boil, as in bouillabaisse, emulsifies the olive oil into the liquid for richness and opacity. Saffron and tomato colour and flavour it; fennel gives an anise note that suits oily fish. The rouille — a garlic, chilli and saffron mayonnaise stiffened with breadcrumb or potato — both seasons the soup and thickens it as it dissolves, while the gruyère melts in for richness.