Sauté the onion in a little oil until translucent, add the diced Smoked Seitan, and sauté a little longer.
Pour in a little water, then add the garlic, red pepper flakes, and spices, followed by the sauerkraut and the remaining water. Cook over medium heat for 25-30 minutes.
Make a roux with the vegan sour cream and flour, then stir it into the soup. Bring to a boil and cook for a few more minutes. Serve with vegan sour cream and fresh bread.