Peel, wash and halve the potatoes and cook in boiling salted water for about 20 minutes. Add peas for the last 3 minutes. Drain the cooking water. Heat 50 g butter and milk. Season with salt and nutmeg.
Add to the potatoes and mash with a potato masher. Season to taste with salt and nutmeg. Meanwhile wash the meat, dab dry and season with salt and pepper. Heat oil in a pan.
Fry the meat on each side for 3-5 minutes. Remove from the pan and keep warm. Melt 50 g butter in the pan. Add fried onions. Cut the meat into strips and put them back into the pan.
Arrange puree and meat on plates.