Cantonese Sweet and Sour Beef

I usually use pork cubes in making sweet and sour meat but since I am saving the pork in the freezer for pancit on Sunday (my youngest daughter's birthday), I decided to use the beef this time.  I've had this before in a Chinese restaurant and the taste was really yum!  The only difference between the two is that the beef one has rice wine vinegar and spring onions.  Oh plus the way it is cooked.  You can compare it to my sweet and sour pork recipe in my past posts.  Both are delicious but have different tangy tastes.  This dish is less complicated to cook than the other one though.   I suggest that you cook both recipes and let me know which one do you like better.

Ingredients
1/2 beef, sliced thinly
1 375 g, pinapple pieces in tin
1 green capcicum, deseeded and chopped
2 stalks spring onions, chopped
1 tbsp garlic, minced
1/4 pineapple juice
1 tsp caster sugar
2 tsp cornflour
2 tbsp dark soy sauce
2 tbsp rice wine vinegar
2 tbsp sunflower oil

Procedure
In a bowl, mix together the pineapple juice, rice wine vinegar, caster sugar, dark soy sauce and cornflour.  Set aside.
Pour the sunflower oil to the beef.  Make sure that the meat is well coated with oil.
Heat a pan. 
Fry the meat for two minutes.
Add in the capcicum, spring onions and garlic.  Sautee for another 2 minutes.
Add in the pinapple pieces.  Cook for another 2 minutes.
Pour in the juice.  Simmer until it starts to bubble.
You can add salt and pepper if you like.

A comment or two will be appreciated...