Long-cooked caramelised onion is a universal technique — it appears in French soupe à l'oignon, in Turkish soğan kavurması, in Palestinian musakhan, in Indian biriyani base, in Italian agrodolce. The technique is the same regardless of tradition: patient low heat over a long period, allowing the onion's sugars to caramelise slowly without burning, producing a sweet, deeply flavoured mass that bears almost no resemblance to the raw onion it began as.
Onions cooked in fat over low-medium heat for 45–90 minutes until they have reduced dramatically in volume, turned a deep amber-brown, and developed a sweet, complex flavour through sugar caramelisation and Maillard reactions at the onion surface.
Deeply caramelised onion adds sweetness, depth, and umami simultaneously — it is one of the few vegetables that produces genuine umami through cooking alone. In musakhan it is inseparable from the sumac and chicken; in French onion soup it is the entire flavour foundation. It asks for acid at service — sumac, vinegar, lemon — to prevent cloying sweetness.
- The cook cannot be rushed — high heat produces browning on the exterior before the interior sugars have caramelised, resulting in bitter, unevenly cooked onion - Salt added at the beginning draws moisture and accelerates the initial softening stage - The onion must be stirred regularly but not constantly — contact with the pan surface produces the browning - The total volume reduction is dramatic: 1kg raw onion produces approximately 200g caramelised onion [VERIFY ratio] - Deglazing with a small amount of liquid (wine, vinegar, water) at any point lifts the fond and prevents burning — this can be repeated multiple times Decisive moment: The colour progression — pale gold at 20 minutes is sweetness developing; amber at 40 minutes is complexity developing; deep mahogany at 60+ minutes is the full caramelisation that produces the musakhan's defining onion. Stopping at gold produces a sweet condiment; stopping at mahogany produces a flavour foundation.
OTTOLENGHI JERUSALEM — Technique Entries OT-01 through OT-25