In a pot, heat oil over medium heat. Saute onions and garlic until limp. Add fish sauce and continue to cook, stirring occasionally, for about 1 to 2 minutes.
Pour in coconut milk and add chili. Bring to a gentle boil and continue to cook for about 5 minutes.
Add squash and cook for about 3 to 5 minutes. Add long beans and continue to cook for another 5 to 6 minutes. Add shrimp and continue to cook for about 4 to 5 minutes or until squash is softened, long beans are tender yet crisp and shrimps have changed color. Season with salt to taste.