Cook green beans in covered pot for 5 minutes in 1 inch of boiling water, drain, rinse under cold water.
Melt butter/oil in a saucepan over medium heat, saute optional ingredients such as garlic, shallot, onion or mushrooms. Add beans and toss thoroughly. Season with salt and pepper, and add optional ingredients such as nuts, seeds, oil, lemon juice or cheese and toss again.