Vegan Bodybuilding & Fitness

I've been vegan for over ten years and feel very well in general. However, I want to lose about 20 lbs, and I also want to build muscle--not just tone up, but add serious muscle. I joined a gym, and the trainer I have seems competent in exercise, but not diet. He basically asked me what I generally ate for breakfast, lunch, and dinner--I told him, and he just wrote down combinations of those foods. (I paid for this?! lol!)

Anyway, I've been trying to research myself, and I read that pre-workout, I should eat slow-digesting protein; and for post-workout, I should eat fast-digesting protein. I did read that soy is fast-digesting, and I have no allergies or problems with soy; but, I couldn't find vegan slow-digesting protein--various articles recommended whey, casein, or egg.

First: Is this correct--slow-digesting protein before workout and fast-digesting after workout?

Second: If so, could anyone tell me a good vegan, slow-digesting protein?

I'm a complete newbie to bodybuilding, so I appreciate any help. Thanks!