Yes, if you use the right thinset. It is harder to do at tile setting time, but is doable. You can use regular thinset up to 1/4" thick and screed it flat first, though, if you wish. Let that cure overnight, then start out with a flat surface. Most pros wouldn't waste the time, and would level as they go. It takes more skill, so depending on who's doing this, and if you want to do the prep yourself, try flattening it first. If the total thickness of thinset is much more than 1/4", though, you are better off with a medium bed mortar (often called granite and marble), since it has more sand in it and can be installed in a thicker bed without the tile sinking. Thinset is meant to be installed in a thin layer...medium bed can be thicker.