Yassa

As tradition built it

Serves 4. Marinated overnight, then 30 minutes.

Ingredients

• 1 chicken, jointed, or firm white fish, or mutton
• 6 limes, juiced
• 1 kg onions, thinly sliced
• 1 tsp mustard
• to taste salt and pepper
• 2 tbsp oil

Method

1. Combine the lime juice, sliced onion, mustard, salt and pepper. Turn the meat through it.
2. Marinate at minimum two hours, ideally overnight, covered, in the refrigerator.
3. Lift the meat out and brown it separately in the oil.
4. Return it to the onion marinade and simmer, covered, 25 to 35 minutes, until the onions have collapsed into a bright, glossy, almost caramelised sauce.
5. Alternatively, oven method: roughly 200°C for 30 minutes covered in foil, then a further 10 minutes uncovered to colour.

What a modern chef changes

The order made explicit, and the mustard named for what it is

Rung 4

Method

1. Never reverse the sequence. Acid marinade first, caramelisation second. Rung 4: the acid inhibits the enzyme responsible for raw onion's harshness before any heat is applied, so the slow cook that follows produces genuine sweetness rather than merely softening sharpness.
2. Layer more than one citrus, as Mory Sacko does at MoSuke in Paris, replacing the single lime with yuzu, kabosu and sudachi. Three distinct Japanese citrus and terpene profiles stack over the same onion base, adding complexity without adding sourness, the acid-discipline lesson of this whole ladder in one dish.
3. Treat the mustard honestly. It is not in the original recipe. Include it if you want the modern, colonial-contact version, or leave it out and season instead with a little more chilli, and know which dish you are cooking either way.