I bought a can of "small fava beans" (it also says "Foule Mudammas," and then it says something--presumably the same thing--in Arabic). I sauteed them in olive oil with a lot of minced garlic and about a 1/2 tsp of cumin. They tasted pretty good, but the skins were really leathery. Are they naturally this way? Did I make this happen by cooking them like this? I've prepared garbanzo beans this way several times without this result.