Preheat your oven to 350˚F, positioning the rack in the center.
Heat 1 tablespoon of vegetable oil in a large skillet over medium-high heat.
Once hot, add half of the lamb pieces and brown them all over.
Remove the browned lamb with tongs and place it in a large Dutch oven.
Layer with half of the potato quarters, chopped carrots, onions, and leeks.
Add another tablespoon of vegetable oil to the skillet and brown the remaining lamb in the same manner, then transfer it to the Dutch oven.
Cover the lamb with the remaining potatoes, carrots, onions, and leeks.
Stir 2 tablespoons of flour into the hot skillet to absorb any fat and juices, cooking over low heat for 3 minutes.
Gradually add 3 cups of meat stock, stirring until the sauce thickens and is lump-free.
Pour this sauce over the lamb and vegetables in the Dutch oven, adding any remaining stock.
Cover tightly with a lid and transfer the pot to the oven.
Let it cook undisturbed for 1 hour.
Afterward, add the thinly sliced cabbage leaves, replace the lid, and cook for another hour.
Occasionally check the stew to ensure the liquid doesn’t reduce too much; add boiling water if necessary.
Season with salt and pepper to taste, and serve hot.