Orokin cells drop on Ceres,Saturn and Deimos so any mission nodes on these planets can drop orokin cells but they can drop in other missions from bosses,stalker spawns and invasion missions. more information on these methods will be included

all bosses have a chance of dropping an orokin cell [including stalker] but the Ceres has a fight with 2 bosses [Lieutenant Lech Kril, captain vor] and Lieutenant Lech Kril has the highest orokin cell drop rate but with 2 bosses you have a higher chance over all and could possibly get multiple per run but if you happen to have any warframes to farm and you need orokin cells this is a viable method

Because normal mission nodes can drop orokin cells this means you can open void relics on planets that drop orokin cells[Ceres,Saturn Deimos] but if you need to level weapons,warframes or companions you can do ''helene'' on Saturn for leveling while getting orokin cells but it can be a bit inconsistent but there is another way to level and get orokin cells a bit more consistently through ''dark sectors'' which are missions with the picture to the right for their mission node and have modifiers that can make resources drop chance increase and the amount of affinity [xp] gained

overall the boss fight on Ceres is the fastest way to gain orokin cells due to both bosses being easy and having a high chance of dropping them but do keep in mind they are not guaranteed so don't expect one to drop every run but if you want them as fast as possible that is the best option but you can still use an extractor at the same time and potentially get more orokin cells at the same time or just get an extractor and not have to do the boss fight.

Thanks for reading and i hoped i helped you in one way or another. If there is anything i missed drop a comment and i will go ahead and edit the guide.