Remove the crust from the bread slice and tear the bread into small pieces. In a large bowl, mix the turkey together with the bread, corn starch, milk, onion, caraway seeds, and salt until combine. With wet hands, shape the turkey mixture into about eighteen 1 1/2-inch meatballs
In a large skillet, heat the oil over medium heat until shimmering. Add the meatballs and cook, turning often, until browned, 5 to 7 minutes. Transfer the meatballs to a plate
Add the garlic to the same skillet and cook over medium heat for a minute or two. Add the mushrooms and thyme and continue to cook, turning often, until the mushrooms are golden. Sprinkle the flour over the mushrooms and stir to coat. Stir in the chicken stock and cook, stirring often, until the sauce has thickened, 5 to 7 minutes
Whisk in the sour cream and mustard until smooth, then return the meatballs to the pan. Turn to coat with the sauce
Spoon the meatballs and sauce over the noodles and serve garnished with the parsley