1 large white onion, halved crosswise, ends discarded, plus 1/2 onion coarsely chopped
5 tablespoons white vinegar
4 baby carrots
1 stalk celery, coarsely chopped
2 pounds ground beef
1 cup rolled oats or breadcrumbs
1 cup white rice
1 cup tomato sauce with garlic
1 cup cold water
1 heaping tablespoon red paprika
1 tablespoon vegetable herb seasoning, such as Vegeta
1/2 tablespoon chicken base
1/2 tablespoon fresh garlic in oil
1/2 tablespoon freshly ground black pepper
Step 1: Preheat the oven to 450 degrees F.
Step 2: Boil the halved onions in water with 3 tablespoons of the vinegar until soft but not falling apart, about 15 minutes.
Step 3: Put the chopped onions, carrots and celery in a food processor andblend until finely chopped. Combine the vegetable mixture, ground beef, oats, rice, tomato sauce, cold water, paprika, vegetable herb seasoning, chicken base, garlic and pepper in a bowl and mix well with your hands.
Step 4: Remove the halved onions from the water and separate into cups. Fill each cup with meat mixture and place meat-side up in a single layer in a 12- by 15-inch baking pan. Mix the remaining 2 tablespoons vinegar with enough hot water to pour into the pan to cover halfway up the sides. Cover and bake for 2 hours.
Step 5: To serve, transfer the stuffed onions to plates and cover with sauce. Serve with a cold sour cream and cucumber salad.