Oriental-style roasted (dark) sesame oil is made from natural sesame seeds that are roasted before the oil is extracted. The taste is richer than that of the lighter variety. Either one can be used for this recipe. Slice the beef by holding the knife on a diagonal angle across the grain. A thin cut provides the best flavor for this quick cooking style. The meat is easier to slice if it’s slightly frozen, and you get nicer slices. KW.