Take the outer savoy cabbage leaves and discard, then cut out the veins and also discard. Dice the remaining head into large chunks. Place in a deeper pot, salt generously and bring to a boil on medium. Boil for 3 minutes and drain. Peel and dice potatoes. Mince garlic.
In a large pot, heat up the oil on high. When hot, add the flour and mix vigorously. Add all other ingredients, 3 cups of water, and bring the temperature down to medium. Stir well, and let simmer for 20-30 minutes.
Serve hot. (Optional) Add a squeeze of lemon.
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Notes
If your savoy cabbage is older, boil it closer to 5 minutes in the beginning. If it's a younger head 2-3 minutes will be sufficient.