I love tempeh!
My favorite way to cook it is ridiculously simple: marinate it a few hours or overnight in a mix of soy sauce, sesame oil, and garlic. (My tempeh comes in planks, and I cut the plank into serving sizes - about the size of a hamburger patty - before I marinate it) Dump everything into a well-oiled cast iron pan, and fry both sides of the tempeh until well browned. The marinade will cook down, you can make a sauce of it if you like.
I eat the tempeh patties plain, or cold and crumbled onto a salad, or served on a bed of rice with a sauce made from the marinade. It's also nice refried in a pan and served with eggs-over-easy for breakfast.
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson