This is very similar to what I make, almost weekly. This week used one large russet and one large sweet potato and 1 onion. Everything was in wedges. I use olive oil. To season them this time I used sea salt, black pepper, red pepper lightly, and cinnamon. The kids loved them. In fact I made them just for me and my left overs for the next day---I had no left overs!
I make all kinds of variations, and they dont turn out crispy really, they are roasted. Butternut squash is great in this--- I dont even peel it, the peel is thin and cooks along with it.