I always use Maroccan couscous. Comes in a very fine structure, medium or a little coarser. Precooked couscous is something I have never heard of! Polenta has a precooked version, don't know about couscous.
There are 2 ways to cook couscous, but, the principle is that all grains need to separate from each other, so, the absorbed amount of water in it needs to be minimal;
- most used method; always measure the couscous. You need only the same amount of boiling water or broth (1/1 ratio), pour over the dry couscous and immediately put a lid on, or, much better, cling film over the preparation. I always use a glass bowl and cover it with clingfilm. Do not stir and let it sit for at least 10 minutes. I usually let it sit for 30 minutes or more. You now have a brittle block of couscous. Put it in a large tray: I use a large lasagnetray. Pick up a handful of couscous at a time and roll it gently between your hands until the grains separate.
Sprinkle some lemon juice and zeste over it, mix in with your fingertips. Add herbs and/or a softened micro-brunoise of fresh vegetables of your choice. Maroccan spicemix Ras-al-hanut seems to be a must. Sprinkle a generous amount of good olive oil over it while mixing in with your fingertops. Reheat if you want. I reheat at 80°C in the oven, in the same lasagnetray, covered with clingfilm! Works perfectly!
- traditional method; a couscoussière is nothing else than a large pot with a steaminsert on top. In the lower pot would be a nice stew simmering with lambshank or leg and vegetables. You can do it with a bamboo insert on a cooking pot if you like. This time the couscous needs to be washed and soaked for a few minutes. Put a mousselincloth or cheesecloth in the insert and put the couscous in it. Steam for a few minutes, get it out, pour on a tray, roll between your hands while hot, add olive oil and keep rolling to separate the grains. Steam again, roll again. Most do this 3 times.