1) To make the sauerkraut, combine all of the ingredients in a Dutch oven or heavy saucepan with a tightly fitting lid. Bring to a simmer, over medium-low heat, cover and cook for 1 hour, stirring a couple of times.
2) For the kielbasa and peppers, combine the water and beer in a large saucepan. Bring to a simmer over medium heat. Add the sausages and cook for 15-20 minutes.
3) Meanwhile, heat the oil in a large nonstick frying pan over a high heat. When the oil is hot, add the pepper slices, sprinkle generously with salt and saute until wilted and lightly coloured, about 8 minutes, stirring often.
Serve the kielbasa with the peppers and the sauerkraut.