Heat the butter in a large skillet with a lid over medium heat; cook and stir the onion and garlic until the onion is translucent, about 5 minutes. Stir in the water, potatoes, carrots, beef bouillon granules, sugar, and caraway seeds; bring to a boil. Reduce the heat to a simmer, and cook until the potatoes and carrots are tender, stirring occasionally, about 15 minutes.
Place the sauerkraut on top of the vegetables in a layer, and place the sausages onto the sauerkraut. Cover, and cook until the sausages are heated through, about 15 minutes.
Whisk the flour into the sour cream in a bowl, and stir into the sauerkraut mixture. Bring to a simmer to thicken the sour cream, sprinkle with salt and pepper, and serve hot.
