Step 1Heat oil in large, heavy soup pot over medium heat. Crumble sausages from casing into pot and break up with spoon. Chop stew meat as fine as possible by hand and add to soup pot. Cook, stirring occasionally, until meats are dark brown, about 15 minutes, but do not scorch.
Step 2Add vinegar and stir. Vinegar will evaporate almost immediately. Using slotted spoon, transfer meat to strainer and shake to remove as much grease as possible. Discard all but 1 tablespoon grease in pot.
Step 3While meat is draining, add onion, carrots and celery to pot and return to medium heat. Cook, stirring frequently, until vegetables have softened and become fragrant, about 5 minutes. Add garlic and cook 2 to 3 minutes more.
Step 4Add lentils and stir to coat with flavorings. Add meat, water, bay leaf, tomatoes and 1 teaspoon salt and bring to simmer. Cook at simmer 45 minutes, until lentils have softened.
Step 5Cut cabbage in quarters. Trim out core and shred cabbage coarsely. About 15 minutes before serving, add cabbage to pot and stir to mix well. Let cabbage melt into pot, then season to taste with a good grinding of black pepper and more salt and vinegar if necessary.