Cilantro no, corriander yes. Fava beans yes, and yellow peas yes, chick peas at least 50% a must. In the sauce mint can be used. Or you can serve the patties with taboli, a salad of parsly and tomatoe.
Hmmm, falafel is an interesting bean dish. I make it half a dozzen times a month. There are a lot of things that can be done to and with it. I also don't just serve it as a main item, but as a side item on plate. There are also variations as you leave the middle east and head towards India (changes in spice, changes in the main bean, but the processe is the same).http://www.icarda.org/Publications/Cook/12/12.html
As to sauce, well, anything really goes. There is a natural foods store up the road that makes a very nice garlic tzatziki that is fab on falafel. Even here, with a simple and traditional sauce, there is a great deal of variations.http://www-2.cs.cmu.edu/~mjw/recipes...ziki-coll.html