1. Peel the potatoes then finely grate the potatoes on the large holes of a grater into a large mixing bowl. Mix in the flour and 1/2 tsp of salt using your hands until a dough is formed.

2. Bring a large pot of water and 1/2 tsp salt to a boil over medium-high heat.

3. Pinch off pieces of the dough about 1 TBSP in size and roll into a small ball. Drop the dough balls (in batches so you don't overcrowd the pot) into the boiling water. Give them a gentle stir and let cook about 3 to 4 minutes, they will begin to float towards the top of the water when done cooking. Remove the dumplings with a slotted spoon and place them in a colander to drain. Continue until all the dough is used.

4. Pour the water out of the pot. Melt the butter in the now empty pot over medium-high heat. Add the cabbage, onions, 1/2 tsp salt, and 1/4 tsp pepper to the pot and cook, stirring often, until cabbage and onions are tender, about 8 minutes.

5. Transfer the dumplings into the pot with the cabbage and onions and toss to combine. Season with additional salt & pepper if necessary.

6. Serve topped with sour cream.