Place potatoes in large pot of salted water. Bring to boil; reduce heat, partially cover and simmer 15-20 minutes.
Meanwhile, begin meatloaf shell:
Heat oven to 350º. Grease a shallow 2 quart casserole dish.
In medium skillet, saute onions in oil for 5 minutes. Add garlic; cook 1 minute. Spoon into large bowl and cool about 10 minutes.
Crumb meat into onion mixture. Add eggs, breadcrumbs, tomato sauce, wine, vinegar, salt and pepper. Mix until thoroughly combined. Place in casserole, press over bottom and up sides to make a shell.
Drain potatoes well. Place in medium bowl. Beat in sour cream, butter, salt and pepper. Add egg and beat until fluffy.
Fill center of shell with mashed potatoes; sprinkle with sesame seeds.
Bake 50-60 minutes until potatoes puff and are lightly browned. Let stand 15 minutes before serving.