Recipe: Tomato Soup with Potatoes

Since you mentioned 'rivels' I will check in my many Amish/Mennonite cookbooks and see if a recipe might be in there. If you could mention what nationality your dear grandmother was; it may narrow down what references we look into. Hope you have good luck!

This may be a good 'base' for the soup you are trying to make....
If you can get homecanned (in Glass) tomato juice, then add some fresh tomatoes, cored/peeled, and chopped fine; this would add tomato bits. Or, prepare the fresh (good and ripe) tomatoes, add just enough water to keep the chopped up tomatoes from scorching in a pan, cook & mash (to force juice out of the tomatoes) until you get the desired quart of tomato liquid; then follow the recipe instructions from that point.

When adding dairy products, make sure the soup is NOT too hot, the tomatoes may curdle the milk/half-and-half/sour cream.

TOMATO SOUP WITH POTATOES (a Hungarian Recipe)

1 quart (4 cups) tomato juice
1 quart (4 cups) water
2 pounds potatoes (or as much as you like)
3 level measuring spoonsful of flour
1 pint (2 cups) half-and-half
2 Tablespoonsful sour cream
1 pint (2 cups) milk
Salt and a little sugar to taste

Clean & cube potatoes. Cook in salted water. Mix tomato juice and water in large enough pot to combine all ingredients. Work flour and sour cream to a smooth paste; adding half-and-half and milk slowly; add to tomato juice and bring to a boil, stirring constantly. Cook about 5 minutes; and cooked potatoes and keep cooking until it (again) comes to a boil. Boil slowly for another 5 minutes.
If too thick, add a little more milk.