Heat oil in a skillet over medium-high heat; add onion and saute until browned, about 5 minutes. Add ground beef to onion and saute until browned, about 5 minutes.
Soak bread in 1/4 cup milk in a small bowl, mash, and add to ground beef mixture; stir in 1/2 of beaten egg, raisins, vinegar, sugar, turmeric, salt, curry powder, and ground black pepper.
Transfer beef mixture to glass baking dish; insert bay leaves.
Bake in preheated oven for 30 minutes. Whisk remaining 1/2 egg and remaining 1/4 cup milk together in a small bowl; pour over meat mixture and return to oven for 30 minutes.
