Tavë Kosi is one of the most famous Albanian dishes. Despite containing yogurt (Kos), the sauce sets during baking due to the eggs, forming a savory, slightly sour, and rich crust that perfectly complements the tender lamb.
It is traditionally served in small earthenware bowls (tavë) in which it is also prepared. However, you can also use one large baking dish. The key ingredient is thick, often sheep or goat, sour milk or thick yogurt.
Place the lamb meat in a large pot, cover with water, add salt and bay leaf.
Bring to a boil, reduce the heat, and simmer covered for 60–75 minutes until the meat is very tender. Skim off any foam.
Remove the meat and strain the broth. You will need 250 ml of hot broth for the sauce.
Preheat the oven to 185 °C (365 °F). Prepare a baking dish (or dishes).
Melt the butter in a large pot or skillet. Add the flour and stir for 2-3 minutes until a light roux is formed.
Gradually pour in 250 ml of the hot lamb broth, stirring constantly. Cook until the sauce thickens. Remove from the heat.
In another bowl, mix the yogurt with the beaten eggs. Pour this mixture into the hot, but no longer boiling, roux mixture.
Taste and add salt and black pepper.
Arrange the cooked meat and raw rice on the bottom of the baking dish.
Pour the Kosi yogurt sauce over the meat and rice. Ensure the meat is completely submerged. Sprinkle with thyme or oregano.
Bake for 45 minutes at 185 °C (365 °F). The crust should be golden brown and the sauce set.
Let rest for 10 minutes before serving.