Step 1: Add the butter to a large Dutch oven or other heavy-duty pot over medium heat. When the butter has melted, add the onion and sauté until translucent.

Step 2: Add the cabbage, carrot, and celery. Sauté until the vegetables begin to soften, stirring frequently, about 3 minutes.

Step 3: Add the bay leaf and vegetable stock and bring to a boil over high heat. Reduce the heat to low and simmer, covered, until the vegetables are crisp-tender, about 15 minutes.

Step 4: Add the potatoes and bring it back to a boil over high heat. Reduce the heat to low and simmer, covered, until the potatoes are tender, about 10 minutes.

Step 5: Add the tomatoes (or undrained canned tomatoes) and bring the soup back to a boil over high heat. Reduce the heat to low and simmer, uncovered, for 5 minutes. Season to taste with salt and pepper.

Step 6: emove and discard the bay leaf from the pot.

Step 7: Serve topped with fresh sour cream and fresh dill.