Cut ampalaya lengthwise and with a spoon, remove seeds and scrape off white pith. Sliced thinly and place in a bowl of cold water until needed. Drain well when ready to use.
In a wide skillet over medium heat, heat oil. Add onions and garlic. Cook, stirring regularly, until softened.
Add tomatoes and cook, mashing with the back of the spoon, until softened and release juice.
Add fish sauce and cook for about 1 minute.
Add shrimp and continue to cook, stirring occasionally, until shrimp starts to change color.
Add water and bring to a boil.
Add ampalaya and gently toss to combine. Cook for about 2 to 3 minutes or until tender yet crisp.
In a thin stream, add eggs and gently stir to distribute. Continue to cook for about 1 minute or until eggs have set.
Season with sugar, salt, and pepper to taste. Serve hot.