On Marion (which is a cute street if you have guests) are Q BBQ and Luo's Peking House, after which Sugar Fixe bakery for a coffee and cookie is nice. Carnivore (if you have a bit more time) is a butcher counter with a few hot sandwiches they'll prepare from scratch.
On Lake Street, Jerusalem Cafe (north) and Khyber Pass (south) have credible buffets, particularly the former (char-grilled chicken thighs especially). Katy's Dumpling House is right there as well - dan dan mein is a great lunch. Nando's Peri Peri for salty Afro-Portuguese or Lou Malnati's for pie if you like slicker productions. Papaspiros (Agora) if you like really schmoozily-served Greek food.
Unusual and worthwhile: Taste of Brazil on Oak Park Ave. south of 290. Cheese bread, blended fruit lemonade, coffee, sandwiches, soups. Sen Sushi is nearby with good set lunches, almost always busy.
These are all Oak Park addros. When I have lunchtime in the region I'm usually just outside the perimeter - Johnnie's, Alpine Sub Shop, Big Guys Berwyn, Axcan, Yum Thai, La Parrillita
, La Quebrada Cicero, Freddy's Pizza.