About 2# of meat                   375 degree oven
About 1.5# of potato
3-4 onions                         ~45 minutes (check after 30)
1# mozzarella cheese
a few blobs of mayo
salt
pepper

Preheat the oven, and get out a 1/2 sheet jelly roll tray. You need at least 1" height on the sides, else it will spill and leak.

Slice the meat into 1"x3" pieces. Slices should be, say, 1/4" thick. Arrange in a layer on the tray. Salt and pepper to taste.

Slice the potatoes, and arrange on top of the meat. More salt and pepper to taste.

Slice the onions (half ring slices) and sprinkle/toss on top of the potatoes.

Shred the mozzarella, and cover the onions with the cheese.

Blob some mayo on top.

Into the oven. Check after 30 minutes or so. The food is ready when the cheese is golden brown, and the potatoes are done. Prick the potatoes with a fork - if soft, you are good to go.

Serve with sour cream, hot mustard, tabasco, etc. Very filling.