Place 20g coriander (leaves, stalks and roots), 1 clove garlic, 2cm piece of ginger, peeled and chopped, 2 teaspoons brown sugar, 2 tablespoons fish sauce, ½ – 1 large red chilli, 2 kaffir lime leaves (central stem removed, leaf finely chopped), and 2 tablespoons lime juice, in a small food processor. Blitz until ingredients are finely chopped and well combined. Alternatively, bash all ingredients (except fish sauce and lime juice) in a mortar and pestle, until a paste, then mix in fish sauce and lime juice. Season to taste with a little more fish sauce or salt if needed.