Tomato and lime bring a pleasing sourness to fragrant lemongrass for this soup inspired by the Thai classic, tom yum. Spice and acid work beautifully with bites of silky pork dumplings to balance the bright flavours for a quick and robust weeknight dinner.
Use the back of a large knife to bruise lemongrass stalk and halve lengthways. Peel and bruise garlic.
Place lemongrass, garlic, lime leaves and stock cube in a saucepan with 625ml (2½ cups) water. Place over high heat and bring to the boil, stirring, to dissolve stock cubes.
Add sambal oelek and cherry tomatoes and reduce heat to medium. Cook for 6–8 minutes or until tomatoes begin to break down.
Cook dumplings in microwave according to packet instructions.
Add oyster mushrooms to soup and simmer for 1-2 minutes to lightly cook. Juice lime and add to soup with fish sauce and sugar. You may like to add a little more sugar or salt to taste, if needed.
Remove lemongrass and lime leaves from soup and discard. Divide dumplings between serving bowls. Ladle over hot and sour soup to serve.