First, prepare the kielbasa. Fill a large pot with deep sides about halfway with water and bring it to a boil. Boil the kielbasa for about 30 minutes to cook it through. Then remove it to a cutting board and drain the water from the pan. Turn the heat off temporarily and let the kielbasa cool enough to handle. Then chop the kielbasa into bite sized pieces and set it aside.
Heat the pan up again over medium high heat and add the dash of olive oil. Let the onions soften for a minute in it, then add the sauerkraut with its juices. Let the sauerkraut lightly brown with the onions for a minute, then add in the beer, two mustards, salt and pepper. Add the kielbasa back in too, then let the mixture simmer for 10 minutes, stirring occassionally. To finish it, stir in the shredded cheddar cheese until it melts in, then take the pan off of the heat.
Fill a platter or separate plates with tortilla chips as desired, then pile generously with the kielbasa mixture. Top the nachos with the chopped pickle and serve immediately! Since this recipe makes a lot, I've devised it so that it is easy to reheat leftovers. Seal any remaining kielbasa mixture in a container and microwave it as needed. Keep the chopped pickles in their own container for topping. Then just pile them on the chips whenever you want a snack!