Step 1: Preparation
1. Wash the ribs with diluted salt water.
2. Marinate the ribs with 1/2 minced onion and garlic, 1/2 teaspoon pepper and 1 teaspoon seasoning powder for about 15-20 minutes.

Step 2: Fry the Ribs
1. Place the pan on the stove, add 2 tablespoons of cooking oil.
2. When the oil is hot, add the ribs and fry them on all sides until golden brown and slightly charred. This will help the ribs to be more fragrant and retain their sweetness when stir-fried. Remove the ribs to a plate.

Step 3: Mix Sweet and Sour Sauce
In a small bowl, mix the sauce mixture including: 4 tablespoons Hoa Hiep fish sauce, 3 tablespoons sugar, 4 tablespoons tamarind juice, 4 tablespoons water. Stir well until the sugar is completely dissolved.

Step 4: Stir-fry the Ribs with the Sauce
1. Reuse the pan that you used to fry the ribs (if there is not too much oil), add the remaining minced onion and garlic and saute until fragrant.
2. Pour in the sweet and sour sauce mixture, bring to a boil.
3. When the sauce boils, add the pre-fried ribs. Stir well to let the ribs absorb the spices.
4. Reduce the heat, simmer until the ribs are tender and the sauce thickens. Stir occasionally to prevent the ribs from burning and to absorb the sauce.
5. When the sauce starts to thicken, add the onions and bell peppers, stir quickly for another 3-5 minutes so that the vegetables are just cooked, still retaining their crunchiness.
6. Finally, slowly pour the diluted tapioca starch/cornstarch into the pan, stirring constantly until the sauce reaches the desired consistency.

Step 5: Finish and Enjoy Turn off the stove, arrange the ribs on a plate. Sprinkle some ground pepper, chopped green onions and coriander to enhance the flavor and aesthetics. This dish is best eaten hot with white rice!