Dice the Leberkäse, season with salt (not too much) and a little pepper and fry in a little butter and let it brown.
In the meantime, chop the onion and add to the pan with the chopped mushrooms. When the onions are translucent, add the tomato paste and sauté briefly. Dust with flour and deglaze with broth. Add paprika and corn to taste and simmer for about 5 minutes. Season the sauce with thyme and oregano.
This goes well with pasta, rice or just a baguette.