Heat a wok over high heat, add the vegetable oil and stir in the shrimp paste. Add the garlic and chili and stir fry for less than 1 minute. Add the dried shrimps and dried scallops and stir fry for less than 1 minute. Add the celery stalks and stir fry for about 2 minutes. Stir in the oyster sauce and sugar and serve immediately.