Looks to me like eye of round (redondo). When done right, like this, its flavor and consistency are excellent. Once you get the formula down don't f with it.
I use high heat for x minutes per kg, then drop it down to very low heat for 10 minutes, pull, cover with foil & towel & rest until ready.
Eye of round has little fat cap & hardly any marbling, so over cooking will dry it out, undercooking will make it tough & chewey.
Basically I did nothing but throwing it in the oven with pretty low temperature (about 70°C) until the meat was medium (around 65°C core temp). After that, searing and putting in tinfoil for another few minutes. All that keeps the meat super soft and very tasty.