Well... Most of the ones stating "Hungarian" cuisine are probably just expensive tourist traps. For cheap and sometimes okay food there are plenty of like eating houses or how to say. I know one that was not too bad at Ferenciek tere at one of the corners, under a corridor if it's still open, but don't prepare for something super cool. I think you better of with a marketplace and cooking. The grat market hall at Lehel tér is especially cool. Also there are cheap and good vietname food there on the galley... ;) And more Hungarian stuff too. There you can grab a Lángos for example at the entrace, that is not that bad. Also the sausage with mustard and some pickles is probably better than most what you can get in the fancy places.