3. For the peanut sauce: Heat oil in a heavy medium pan over medium heat. Add shallots and garlic and cook until soft, about 3 minutes. Stir in shrimp paste, mashing with the back of a spoon, and cook for 1 minute. Add stock, bring to a boil, then stir in ground peanuts, kecap manis, ginger, chiles, and sugar, and simmer, stirring often, until sauce thickens to a loose paste, about 20 minutes. Keep sauce warm over low heat, adding lime juice just before serving. (Add a little water to thin sauce, if necessary.) Transfer sauce to a serving bowl.