Line large plate with paper towel. Heat 1 tablespoon vegetable oil in Dutch oven over medium-high heat until shimmering.
Add 14 ounces kielbasa sausage, sliced ½ inch thick, and cook, stirring occasionally, until lightly browned, 5 minutes. Using slotted spoon, transfer sausage to prepared plate.
Add 1 pound Yukon Gold potatoes, peeled, halved, and sliced thin; 1 onion, halved and sliced thin; ½ teaspoon table salt; ¼ teaspoon pepper; and ¼ teaspoon baking soda to now-empty pot and stir to coat.
Add 4 cups chicken broth and bring to boil. Cover and continue to boil, stirring occasionally, until onions and potatoes are very soft, 5 to 6 minutes.
Off heat, use immersion blender or blender to process until smooth, 1 to 2 minutes.
Stir in 3½ cups green cabbage cut into 1-inch pieces, and return to simmer. Cook, stirring frequently, until cabbage is crisp-tender, 6 to 8 minutes.
Off heat, stir in kielbasa, ⅓ cup sour cream, 2 tablespoons chopped dill, and 2 teaspoons Dijon mustard. Season with salt to taste.
Ladle into 4 bowls. Divide remaining ⅓ cup sour cream, 1 tablespoon dill fronds, and ¼ teaspoon smoked paprika among bowls. Serve.
