Soto Ayam Lamongan with Koya

The crumb topping that finishes the soup

Soto ayam Lamongan is a chicken soup from Lamongan, in East Java, distinguished by koya: a fine crumb made from shrimp crackers and garlic. That little addition transforms the bowl more than you might expect at first. The broth is savory and fragrant, with turmeric giving it its yellow color; koya adds a salty, shrimp-rich flavor and a light, almost powdery texture. Rice vermicelli and bean sprouts make the soup more filling, while lime provides a fresh contrast.

The base is a spice paste, or bumbu, made with shallot, garlic, turmeric, ginger, candlenuts and coriander. Candlenuts give the paste a mild, rounded flavor and a little body, but the soup will still be good if you leave them out; the broth will just be a little less full-bodied. Cashews are a handy substitute, although they taste a little sweeter. Cook the paste gently in oil until fragrant and the raw smell has gone. This step deepens the spices and keeps the broth from tasting flat or sharply of raw onion.

Bone-in chicken gives the broth more flavor than chicken breast and stays juicy as it simmers. Chicken thighs are practical and easy to pull apart after cooking. Keep the broth at a gentle simmer rather than a hard boil: this helps it stay clear and keeps the chicken from drying out too quickly. Lime leaves and bruised lemongrass add a fresh, citrusy aroma. If you can't find candlenuts or lime leaves, you can leave them out; don't simply add extra turmeric to make up the difference, as it mainly provides color and can taste earthy if you use too much.

Shrimp crackers are the key ingredient in koya. Grind them with roasted garlic to make a fine crumb that isn't completely powdery. Without shrimp crackers, you won't get the same savory flavor; crumbled, mild-flavored crackers can add some crunch, but they aren't a like-for-like substitute. Keep the koya dry and serve it separately, as it softens quickly in hot broth. You can also serve the vermicelli, bean sprouts, finely sliced cabbage, egg and lime separately, so the vegetables stay crunchy and everyone can choose their own proportions.

Serve the soup as a complete lunch or a light evening meal, with extra lime and, if you have some on hand, fried shallots. Rice vermicelli usually only needs soaking or a brief boil; follow the package instructions and rinse it if needed to stop it cooking further. Refrigerate leftover broth and chicken in a covered container within two hours and use within three to four days. Store the dry koya and the other toppings separately. Reheat the soup thoroughly and add the fresh ingredients only once it's in the bowl.