Earth Balance is the best vegan margarine, or Organic Smart Balance. You can't always find those at an ordinary grocery store; you might have to go to a place like Whole Foods. Either way, they're pretty expensive. If you don't have margarine, use oil instead.
Cashew and Green Bean Pasta
3/4 c cashews
6 T margarine or oil
1 to 4 10-oz bags frozen green beans
3/4 - 1 lb pasta (rotini is nice)
Steam green beans. Cook pasta. Add a little pasta water to thin the cashew sauce.
Mix all together. (Add optional parsley.) Add salt and especially pepper to taste.