One Day Cheap Eats in Houston??

I'm visiting for the second time in my life and i'm a hardcore food lover, but this time I have a very limited budget. Last time I visited Pho Saigon looking for their Bahn Mi. Unfortunately they didn't have the bread that day so I ended up trying their amazing Pho.

I'm going to do one of my meals there again but I was wondering if you could recommend extremely cheap and delicious food around midtown and/or montrose. What would be 2 must-visit places?