Rub cabbage with a little bit of salt (about 2 teaspoons) and let it rest for 10 minutes.
Peel the onion and cut Julienne.
Cut the bacon into cubes.
In a large pot, brown the bacon in 1 tablespoon oil.
Add onion and sauté.
Add cabbage gradually, one handful at a time and sauté. When the first batch is soft, add more cabbage. Do the same until you're done adding the whole cabbage.
Add tomatoes, thyme and bay leaves.
Cover the pot and simmer on stove over medium heat (or in the oven) for about 40-50 minutes. If at any point you think the cabbage is too dry, add just a little bit of water and mix.
Add the tomato sauce and cook for 10-15 more minutes, until no sauce is left.