1/3 to 1/2 cup white sugar (depending on how sweet you like the sauce)
1/3 to 1/2 cup rice vinegar (depending on how sour your like the sauce)
1/4 cup ketchup
1/2 teaspoon soy sauce
1 cup pineapple chunks with natural juice, preferably not syrup
3 tablespoons cornstarch
1/4 cup water
2 green onions cut diagonally in 1 inch pieces (for garnish)
How to make it
Place salt, sugar, soy sauce, egg white, chopped green onions, garlic, and ginger in a bowl. Whisk together until egg white is slightly foamy. Add pork cut into 1 inch cubes. Marinate for at least one hour stirring often.
Put about 2 tablespoons of oil in a frying pan. Heat over medium high heat. Add onions and green pepper. Sauté until the vegetables are cooked through, but still crisp. Remove from the pan. Put the vegetables to the side with the tomato.
Make the sweet/sour sauce: In a saucepan, mix water, salt, sugar, vinegar, ketchup and soy sauce. Bring to a simmer. Set aside. Make a slurry of cornstarch with 1/4 cup water. Set aside. (A slurry is a combination of cornstarch and cool water. It is a common thickener for Chinese cuisine.)
Coat the pork with cornstarch, and fry in ta few tablespoons of oil until evenly browned. Drain on paper towels.
Wipe out the frying pan. Add a tablespoon of oil. Combine the vegetables and pork including the tomato wedges. Heat thoroughly.
Reheat the sauce adding in the pineapple. When simmering, add the slurry and simmer until thickened.
Place pork and vegetables in a serving dish. Pour sauce and pineapple on top. Serve very hot over white rice. Garnish pork with green onions