Can Sephardim warm up cold pasta with sauce on Shabbat over a blech (metal sheet used to cover stovetop burners) if it was fully cooked on Erev Shabbat?
It is controversial among the Sefardi poskim what the halacha is. According to R’ B. Z. Abba Saul zt”l (Ohr L’tzion chap. 30-13 ftnt. 13), R Y. Abadi shlit”a (Ohr Yitzchok O:Ch 163) that it is not permitted, however according to R’ Ovadia Yosef zt”l (Yalkut Yosef Shabbos 3-55, also see Yaskil Avdi) that it is halahically permitted however it is commendable to be stringent regarding this. Most Ashkenazi poskim rule that there is even if the liquid in the dish is the minority, it will still be considered cooking it and it is not permitted.
What you can do according to all poskim, is to warm up the dry cold pasta on an upside down pot on the blech, even if it will get hot, and the sauce can be placed next to the blech, (if it isn’t mixed already with the pasta) or in a place that it cannot become yad soledes bo over there, (even if it is kept there for a long time). This way your sauce will at least be lukewarm.
O:CH 318-4, Pri Megadim Eshel Avrohom 318-39, Graz 318-9, Igros Moshe O:CH 4-74, bishul-7, Shmiras Shabbos Khilchoso 1 ftnt. 126, M:B 253-68. The controversy is based on what R’ Yerucham, quoted in the Bais Yosef siman 263, as saying that “Anything that has “Rov” liquid may not be reheated, however in siman 381 he quotes R’ Yerucham as saying “Anything has (any) liquid in it” may not be reheated. In fact in Shulchan Aruch 318-15 the Maran writes, “A solid that is precooked and dry, that it has no liquid in it, is permitted to reheat”, also see 318-4. He doesn’t say that if it is mostly solid that it is permitted. Therefore there are poskim (Tevuos Shamesh O:CH-5, Hagahos R’Y. Hamburger on the Bais Yosef (siman 253), Ohr L’tzion ibid, Ohr Yitzchok ibid, who say that what was quoted in siman 263, is a printing mistake. (R’ Ovadia zt”l also gives other rationales for his psak, see Yalkut Yosef ibid ftnt 66.) R’ Ovadia keep the understanding as it is quoted in siman 253, together with some other considerations. Most Ashkenazi poskim rule that even if the dish has a little liquid, it may not be reheated on shabbos