I barely steam the green beans first. Then in a skillet, I warm the olive oil and soften the garlic and mustard seed (don't cook too long or too hot, as the seeds will pop and the garlic will brown...which you don't want). Then I add the green beans, sauteeing them till they're done. Just before serving, I sprinkle freshly ground salt and pepper, and sprinkle a little lemon juice over all.