Put the canned beans and chick-peas with their liquid into a saucepan and boil about a minute over medium heat. Strain the liquid from the beans and chick-peas. Put the beans and peas into a salad bowl. Cut the knockwurst into 1/4" slices and then quarter the slices. Add to the salad, then add the onions and salt.
Pour the olive oil into the blender, add the wine vinegar, garlic and parsley. Run the blender until the parsley is finely chopped, perhaps half a minute. Pour this dressing over the salad. Mix it all together gently but thoroughly. Chill the salad in the refrigerator for several hours before serving.