bro if you ask me, just cut the visible fat you see in the meat and you'll be ok. Steak has a lot of fat in b/w layers of meat that you can't take out, so just take out the ones you can see.
LB is a pretty thick cut, it's available anywhere here in the US. Not sure about The Netherlands jaap. But because it's usually cut pretty thick, a GF grill wouldn't work unless you sliced it up yourself first. I'll either bbq it or broil it.
a Proffesional chef taught me this trick to TENDERIZE it.
1. Trim all visible Fat.
2. Cut a 8-10oz portion of the meat in reaaaaally thin strips.
3. Soak it in Lemon Juice for 15-30 min prior to cooking. The acidity of the Lemon Juice actually cooks the meat somewhat, but it gets superrrrrrrrrrr tender.
4. Grill it on a REALLY hot grill or a couple of minutes on each side.