I must have missed your mention of Bucktown. I'll take that to mean that you're fine with a large part of the city outside of downtown.
If heat is your primary concern, which I'm gathering that it is, then you simply need to follow the raw chile.
There are some great Thai restaurants with excellent dishes that feature uncooked chiles: the Issaan sausage at TAC immediately comes to mind for it's garnish of raw finger chiles. Also, a papaya salad at the same restaurant, ordered "spicy", will surely satisfy you. There are plenty of other spicy dishes on the Thai menu there to satisfy you. Be sure to let them know your spice preference.
Here's a link to the translated Thai menu there. There are tons of other threads about their food. A search for "TAC" will yield many.
If you want to stay Mexican, Carlos at
Sol de Mexico makes a very good cochinita pibil with a habanero salsa that is excellent.
Or maybe a
habanero dog at U Lucky Dawg is what you're looking for?
That's all I've got for now.
Best,
Michael