Step 2

Put the onion, tomato, chili, galangal, lemongrass, shrimp heads and bouillon cube into a large pan with the water. Bring it up to a boil over high heat.

Step 3

Drop it to a simmer and leave it for twenty minutes to reduce. The broth should go cloudy and smell sharply aromatic.

Step 4

Lift the shrimp heads out with a slotted spoon and discard them, leaving the vegetables in the broth.

Step 5

Stir in the mushrooms and lime leaves and cook over medium heat for three minutes. They should soften without turning slippery.

Step 6

Add the sugar, fish sauce, lime juice, coconut milk and shrimp. Bring it just to a boil and take it off the moment the shrimp turn opaque.

Step 7

Lift out the lemongrass and stir the chili jam through if you are using it. Scatter cilantro over each bowl as you serve.