With small sharp knife, cut each sprout into 3 or 4 slices. (The sprouts can be sliced, covered and refrigerated 1 day ahead if desired.)
Drop sprouts into medium saucepan of boiling salted water. After water returns to boil, cook sprouts until crisp-tender, about 2 minutes; drain.
Toss with butter, lemon juice, salt, white peppper and cayenne.
Brussels sprouts have been the most maligned of vegetables probably because they are usually overcooked. If cooked quickly, they will retain their pleasing yellow-green color and crisp texture.