You will need a 7 to 8 quart pan with lid that can go from stove top to the oven. Clean and Dice the onion and cut the Cabbage into thin strips. Melt the butter in the 7 quart pan over medium heat.
Add onions can cabbage and saute until onions are just tender.
Remove from heat and add Sauerkraut, tomatoes, beer, stock and Carraway Seeds. I use my hands. Return the pan to the stove and bring mixture to strong simmer for 15 minutes, stirring often. Remove from heat and make a hole or well in the center of the Sauerkraut mixture to hold the Pork Roast. About half of the roast should be visible above the Kraut.