I think Ultima's info in the initial post needs a little cleaning up, it's a little more simple than that (and the actual example mentioned is also kinda....yeah.). It's not necessarily wrong, but....sandoori isn't a 7 way mixup lol
Sandoori is a generic type of mixup, independent of a character's moveset, that allows them to crossup (usually) three ways (which is why it is called SAN doori): crossup, no/fake crossup, and a high/low (whatever the other two aren't) or a throw. The moveset of the character can allow them to go from a correct sandoori guess into another sandoori setup, and also determines if that last option is low or throw. A true sandoori can be done anywhere on the screen outside of in the very corner.
Another very notable thing about sandoori that makes it so strong is that the common airdash-back-over option is very safe from all kinds of reversals: if the air attack was meaty, heats often miss and get punished; dodges are usually safe from the air attack but lose to the throw and the low or throw option and rolls kind of lose to everything; stuff usually very reliable like MBAC ciel ex flashkick => cancel to ex knives do not work to the air option.
Examples are, as mentioned, (MBAC) Kouma 214a, (MBAC) Hisui close strong knockdown, and also (MBAC) Sacchin 623c (denpa uses this).
MBAC Kouma:
(From the left side), 214a, and then dash forward, jump straight up. Your momentum will carry you to the other side of the opponent. From here, you're in a position for all three options: Air backdash j.C for a left-side hit, land and 2a for a right side hit, or land and grab (kouma doesn't hit low). The positioning is really what makes the sandoori here: in range to land a ground hit, in range to land a grab (kind of difficult), and in range to combo off of air backdash j.C (also kind of difficult).
http://www.youtube.com/watch?v=ZA0EP-QSHjg This only has one option/instance of the example and some other ambigous crossup off 2c but it gets the job done.
MBAC Hisui (with my limited and possibly incorrect knowledge):
Off of a throw, Hisui has the exact same setup with the exact same options working the same way, except she follows the air j.C differently.
MBAC Sacchin:
623c. Superjump, neutral jump up after you've crossed up, and forward jump momentum back toward where you started. Sacchin then has: Airbackdash j.C high hit, land right side low hit, land left side low hit. Note that this is different than her 4-way.
http://www.youtube.com/watch?v=h8Erg_a4HDo#t=55sAgain, the thing with achieving sandoori with your character, because it is mostly independent of moveset, is more on gaining a nice knockdown and achieving that positioning before the opponent gets up. Getting a usable sandoori is actually dependent on moveset, however: being able to combo off the options and get good damage and, most importantly, being able to go from a sandoori into another sandoori.
I don't understand why people think jumpover air jump air backdash in the corner j.C is a sandoori/real mixup...it's perfectly reactable even when done very cleanly.
A more practical, newer example I recently discovered with F-Kouma (thanks goes to zar for using this back in friggin mbac ps2 days? lol):
(From the left side), 214a -or- 623a, dash superjump, timed airbackdash. Timed early, j.C for left side hit; Timed late, j.A/B/C whiff for less landing recovery, 2aa for right side hit; Timed either way, land 214a. Much harder than what MBAC Kouma had to do but it's still around.