A really good po' boy can be tough to find in Chicago, but one that I'd be happy to have again is the Shrimp Po' Boy ($9.50) at DeLux Bar & Grill. It may not be the most traditional one I've encountered, but that may be where the success of this sandwich began.
For starters, they use small, lightly breaded popcorn shrimp instead of a larger variety. This ensures every bite gets some shrimp in it, which makes every bite taste as good as the last. The breading is heavy on the black pepper and garlic, and it's just enough seasoning to compliment all the other flavors going on. It's topped with a small amount of coleslaw that is vinegary but also has lots of coarse ground mustard, which is a nice divergence from traditional slaw. It all comes on a soft, French roll that holds the sandwich well and is crispy on the outside and doughy on the inside. It doesn't impart much flavor of its own, but that's a good thing in this case. Sriracha mayo is spread generously on the top bun and lends some serious spice—I could dip just about anything in this sauce and be a happy girl (and trust me, I've tried). Thick slices of tomato and some shredded lettuce lend some freshness and acidity to round out the sandwich.