In a small bowl, combine the fish sauce, lime juice and sugar; then stir until the sugar is mostly dissolved. Add the garlic, shallots and chilies. You can use this sauce right away, but it's best to let it sit for at least 10 minutes to allow the flavours to infuse. (See blog post for storage)
1 ½ tablespoon fish sauce, 1 ½ tablespoon lime juice, ½ teaspoon sugar, 1-2 cloves garlic, 1 tablespoon shallots