Combine sugar and kosher salt in a small bowl. Combine smoked salt and smoked pepper; rub on beef. Place in a deep pan, and cover with sugar mixture. Chill, uncovered, 2 days, turning beef occasionally.
Remove beef from curing mixture, wiping away all residue. Wrap beef in cheesecloth, and hang above a bowl in the refrigerator (to drain away liquid) 8 hours or overnight.
Cut beef into very thin slices. Top baguette slices with beef and Pickled Onions.