Remove the meat from the broth, cut it and return it to the pan.
Sprinkle the broth with salt.
Thinly slice the cabbage and put it in the broth.
Add tomato paste to stewed vegetables. Ideally, of course, it is better to add tomatoes, but if they are good and fleshy, they are real. I think tomatoes give borscht color, not vinegar.
Be sure to add a sugar-sweet note to the borscht.