It is usually more satisfactory to buy the meat and have it ground by the butcher, than to buy meat which has been ground in advance.
Then you know just what kind of meat goes into your hamburgers.
Some prefer their hamburger ground twice.
Combine butter and oil in large skillet, and heat slowly until fat begins to smoke.
Shape beef into 6 patties about 1/8" thick.
Quickly brown 3 or 4 patties at a time on 1 side in the butter; turn, and brown other side. (This takes about 2-2 1/2 min on each side.)
Remove to hot platter; spread surface of each with 1 teasp of the softened butter; and sprinkle with salt and pepper.