What were you planning to use the sweet and sour sauce for? Pork (ribs)? Chicken? Fish?

One standard recipe I use is very simple and you can modify it to your taste. For every cup of tomato sauce, use about 2 Tbsp of white or apple cider vinegar, and 2Tbsp of brown sugar in a small pot. If you use catsup in place of the tomato sauce, cut back on the vinegar and sugar (the catsup has vinegar and brown sugar in it, too).

Heat through until the sugar has dissolved completely. If you're doing something like pork ribs in a sweet sour sauce, you can also add one small can of pineapple chunks (use some of the juice the pineapple was packed in and cut back on some of the brown sugar).

Again, the sourness you control by adding more vinegar if it's not sour enough. If you're doing pork ribs, another good ingredient to add in is chopped green peppers (dice them into 1" chunks) and add them to your sauce about midway through heating it up so they'll still be crunchy when you serve it.