One of the treats of shopping in Oaklands Chinatown is a Vietnamese sandwich from the venerable Cam Huong for a cheap and fast lunch. Even though the heavy hand with black pepper and mayo and the chewy bread keep it from being my top choice, the range of interesting combinations offered here and robust flavors always strike a satisfying chord with me.
Recently I tried the grilled beef and onion sandwich recommended by ericf filled with finger-sized rolls of thin slices of beef wrapped around fine shavings of onion. The marriage of the highly seasoned charred beef with the sweetly pungent and barely wilted onion packs a wallop. You have to really like onions to appreciate this one. If you do, this is extremely delicious music for your mouth.
Just remember to use some breath mints.