Ashkenazim are not concerned for meat being unwatched for a few minutes as per the Ramah. I want to know do Sefardim have this concern? Meaning, in a work situation, when a Sefardi puts a meat sandwich in the company refrigerator, can they eat it?
The Shulchan Aruch Yoreh Deah 63, based on this Rambam and this Gemara in Hullin 95a and 95b, rules that the thing we are worried about is an animal (according to rashi a raven, according to the rambam "a wild animal or vermin" (my rough translation)) switching the meat. The gemara holds that this doesn't apply if it was in the hands of a non-Jew. In a workplace refrigerator, even though non-Jews have access to it (and technically can switch it), it is sealed off from animals (or any force that can move it besides people-I dont think "a raven" is literally only a raven). Furthermore, this din doesn't apply if you can recognize your meat (teviut eyna), which may be true if you made the sandwich (i.e. size/shape of the slices).
If it is left in a place accessible by animals, such as a picnic table or a house with open windows, and the eater cannot recognize that this is his meat, and there is no seal, a Sepharadic Jew would generally refrain from eating such meat based on this Maran. In special cases, poskim are lenient.
In conclusion, a workplace refrigerator should have the din of a place unaccessable by wild animals or vermin, which the Shulchan Aruch says is not a problem. Non-Jews shouldn't make a difference based on the gemara. This is based on my understanding of the gemara, Rishonim, and Shulchan Aruch. As always, please CYLOR for a pesak din.
EDIT: The Shulchan Aruch (63:1) rules, unlike the gemara referenced above, that we are also worried about non-Jews in terms of basar shenitalem min ha'ayin. The GR"A (S"K 1) says that this is based on the Rambam, who rules like the Yerushalmi in Shakalim 7:2 NOT on the Bavli I quoted above. This din can also clearly be seen in the Rambam Ma'achalot Asurot 8:10.
To reconclude, unless you can recognize your meat, there is some seal, or it is unlikely that a non-Jew had access, and is impossible that a wild animal had access, a Sepharadic Jew should refrain from eating it.