We don't love big rumps as they have a small problem which is due to the fact that as the animal gets older the connective tissue "calcifys" which means gets harder and gristlier.
Now the rump consists of 4 muscles (see pic) all of which are covered in silverskin and there is a little bit of gristle around the place as well. So as a piece of meat it can suffer from the impression of being tough despite it not being the meat but the connective tissue that has caused the problem.

Now there is 2 ways to deal with this problem
1) trim every skerrick of connective tissue off
and
2) get the temperature of the connective tissue above 65 deg C at which point it will go soft so long as the cut in question is from a well fed and reared beef animal not some broken down old cow.
On the weekend I used both methods
Firstly and simply I made a version of steak tartare with completely denuded rump tri tip and eye of rump side. I made a spice blend with cinnamon, allspice, black and white pepper and salt. I then got some fine bulgur and washed it then pulsed it in a blender with a dash of olive oil till it was a fine paste. I pulped a few slices of red onion then blended my rump again to a paste like consistency.
I then worked the bulgur, red onion and meat paste together by hand adding the spice mixture as well. This was served with oven toasted pita bread

The remainder of the rump once trimmed was liberally doused in olive oil, scored and had salt rubbed into the fat. This was placed in a weber well stocked with real charcoal.
Set and forget and 3.5 hours later - it doesn't get any better than this
