Serious Eats - seriouseats.com

How about heavy metal hamburgers?
Kuma's Cafe. Seriously, some fantastic burgers there and it's wacky, i.e. highly tattooed and pierced staff. Be prepared to wait.
I also make sure to eat some Mexican food every time I'm back in Chicago... Frontera Grill is awesome as expected, and I also like De Cero at Randolph and Halsted... among other things you can get a taco sampler platter there and choose from some creative, deeelicious tacos.
For steak and potatoes that are outside of the normal "old boy's club" steakhouse, I'd send you to Tango Sur, an argentinian steakhouse on Southport near Byron. Southport is a fun street to walk up and down as well. And you're just a hop and a skip from Wrigley Field there as well.
Dear god, I miss Chicago.

Definitely go for pizza. I used to love Due's, but I feel the quality has slipped slightly since Uno's became a national chain. I love Malnati's and Gino's as well for deep dish, and Edwardo's for stuffed pizza.

There are some nice restaurants near Lincoln Park Zoo, including R.J. Grunts, which is perfect for lunch. Great sandwiches, good service, huge menu, excellent prices. Very relaxed, fun place.

You could also try street food; find a likely-looking hot-dog stand, or Gyros or Italian beef. All Chicago classics. Try your dog 'dragged through the garden' (with everything) or grab a 'cheesy beef, dipped, with peppers' (an italian beef with sport peppers dipped in gravy).

I'll also tell you the least hidden secret in Chicago. Go to the Hancock Tower, and take the ear-popping ride to the lounge. Have an over-priced drink and enjoy an amazing view without paying the admission fee for the observatory deck, which is one floor up. It's all tourists and the drinks are a rip-off, but you can sit right by the window and look out on the lake.

well, you're not going to find a hot dog cart or any sort of licensed street vendor in chicago, they're illegal.
in the loop, America's Dog has a good Chicago Style dog, in River North, i'd hit the super-touristy-but-still-turns-out-a-respectable-dog Portillo's. don't you dare order ketchup on it!
i would have also put Hot Doug's (sausage superstore and encased meat emporium) on your list right off the bat, but it didn't strike me as a steak and potatoes kind of place. but have a look at his specials menu anyways.

take a look at the serious eats chicago guide. it's right on the money.