INGREDIENTS
2 tbsp
olive oil (divided)
1
onion (diced)
2 lb
ground beef
1/2 cup
bread crumb
2
large egg yolks
1/4 tsp
ground nutmeg
1/4 cup
unsalted butter
1/3 cup
all-purpose flour
4 cups
beef broth
3/4 cup
sour cream
Kosher salt and freshly ground black pepper (to taste)