There are probably dozen of steak restaurants in Brussels, but for me La Braise in the Saint Gilles commune is the best.
It’s a nonpretentious, simple, straightforward restaurant where you go to eat meat. Good local Belgian meat.
The menu is short: spare ribs, steak, entrecote, grilled chicken. But I never tried any of those. When I go there, I always eat the “côte à l’os”, the T-bone steak. It’s served in 2 sizes: 600g for 1 person or 1200/1300g for 2 persons. The meat is so good and cooked to perfection that you can eat your fair share of 1200g without struggling. At least I do, and my friends too.
Most times they do have some different cuts, like aged meat, it’s worth asking. It’s obviously a bit more expensive but it’s worth it.
The restaurant inside is small, it has place for 20/30 customers max. It has a terrace that nowadays is bigger than usual. But I suggest you book a day in advance as spots get taken quickly especially on the weekend.