I did used a Kitchen Aid grinder attachment to make chopped meat for
hamburgers and it was very simple and most of it went into the
dishwasher. I was just going to by ground sirloin at another market
but it's a zoo there so I decided to get three pieces of sirloin cut
for london broil. I ground in everything and didn't trim it at all.
I used the metal extruder plate with the small holes.

After I was finished, I mixed it all together with my hands not for
too long and maybe not long enough. I made hamburgers that were 1/3
of a pound each but I felt that I didn't compact them enough.

Out of 10 people who were there, 9 wanted their hamburgers medium to
well. I should have made mine after everyone else's because I like
mine medium rare. I was disappointed with the taste. I don't know if
it was from one of 3 reasons or maybe all of them.

1. Perhaps I didn't mixup the meat enough after it was ground.
2. Perhaps I didn't compress the patties enough. It seemed as though
they were to soft and almost flakey.
3. Perhaps sirloin london broil doesn't make good hamburgers as it
might be too lean. I had no way of measuring but the meat could have
been 95% lean and that is too lean for a good hamburger. .
4. Maybe it was just a little too overcooked but I don't think it was
only that.

Can you make hamburgers out of london broil or meat cut for steaks?
Will the fat content be too low and if so, what do you use? Before I
saw the sirloin, I was going to try top round and skirt steak. Maybe
I should have mixed the skirt steak with the sirloin.