For the sauerkraut, dice the onion and slowly roast in lard until light brown. Rinse sauerkraut a little under cold water.
When the onions are light brown, add the spoonful of sugar, stir once, add flour, also stir and pour about 1/4 liter of water or soup.
Add sauerkraut, cook a little. Season to taste with salt and pepper.