In a hot oiled wok, brown the marinated pork and scallion, reduce to medium high heat and cook until about done.
Add onion and stir fry until onions are tender.
Add a dash of white cooking wine and tomatoes.
After a few minutes, add the sweet bean sauce, diluting it with a bit of hot water in the can.
Then swirl in the hot bean sauce, and water or stock.
Bring to a boil, reduce to simmer, and cook uncovered for at least an hour until the sauce reduces, stirring occasionally.
Adjust seasonings with sugar and soy sauce to taste.
Remove from heat and serve warm or room temperature.