I (Britt) learned how to make plantains from a Haitian lady and I can share how I was taught to prepare them.
There is one major-ish problem though. In the states, most grocery stores carry plantains (if you look hard enough - usually several bundles by the bananas), but they are most often imported from places like Colombia or Costa Rica --- places where there is a lot more rain and thus different than the plantains here (drier climate = drier plantains, which are better for the recipe below.) When I tried to make plantains for my family in MN in August - I used Colombian imports and the end result was very different from Haitian plantains. My family still liked how they tasted - but don't expect it took look or taste like what you've had/seen from here.
First: -Peel plantains (usually must be done w/ a knife - or you can crack along the ridge w/ your thumb nail and pry it off that way)
-Cut each plantain(horizontally) at an slant/angle into four, semi-equal pieces
-Fry in vegetable oil until golden yellow (or take one out and test it - must be soft enough for next step)
-Smash into circular patty (this is also where I struggled w/ the stateside plantain preparations ... in Haiti we have a special wooden smasher thing that works perfectly ... try using the bottom of a measuring cup or anything flat and round. Flatter they are, the crispier the plantain and vice versa)
-Dip smashed circular plantains into a mixture of previously prepared vinegar and water and salt & 1-2 chicken bouillon cube --- about 2 parts vinegar for 1 part water. Then just kind of pour in salt until it tastes right. I'm not sure what the bouillon does, but I always use it. This step is optional, but I personally think it makes the plantains taste way better and less boring.
-Re-fry seasoned/non-seasoned plantain patty. Fry to preference - the longer you leave them in, crispier they will be.
If you do the vinegar step, then it is definitely not necessary to add salt on top of them at the end. Eat w/ ketchup = tre bon gou!
Also -- I would start with about 6 plantains ... that would feed about 4-6 people, as a side-dish/snack size portion.
Hope that makes sense; email me at email@example.com if you need more direction. Good luck!