Preheat the oven to 320 F. Mix salt and spices, rub the rolled lamb breast on all sides with your mixture. (If the lamb breast is not rolled, rub it on both sides, then roll it up and tie it with a cooking string.)
Add 1 tbsp olive oil or other frying oil to the hot skillet. Sauté onions and carrots for 5 minutes over medium heat, stirring occasionally. Then add the garlic and fry everything together for another 2 minutes.
Add more olive oil to the pan and fry the rolled breast over high heat, gradually turning it with cooking tongs, until you get a fried crust over the entire surface.
Transfer to a 9 x13" baking dish, also add the fried vegetables and slices of lemon pieces. Pour in the beef broth and add the thyme.
Cover the baking dish with foil and place in the oven for 1 hour, take out the lamb, remove the foil and spoon some of the broth over on top. Cover with foil again and continue roasting for 1 more hour.
Then remove the foil, cover the lamb with broth and bake without foil for 30-40 more minutes to make the crust darker. (internal temp should be 145 F before consuming)
Remove, let it rest wrapped in foil for 15 minutes before slicing.
You can blend the broth with vegetables in a blender and serve the sliced lamb breast with this sauce.