Season ribs with salt and pepper.

Fill a large saucepan with water. Add the ribs, onion, and additional salt and pepper and bring to a boil over high heat. Boil uncovered for one hour.

Remove ribs to baking pan and reserve cooking liquid.

Preheat oven to 325 degrees Fahrenheit.

In a medium mixing bowl, combine tomato paste, garlic powder, vinegar, sugar, and salt and pepper. Add half a cup of cooking liquid and whisk to combine. You may need to add more or less liquid. The sauce should be thick but pourable.

Spoon sauce over each rib. Cook uncovered for 20 minutes to glaze.