I stick strictly to low-residue foods when I'm flaring. When not flaring, I can eat pasta with tomato sauce, but in a flare the pasta has to be plain or with a little butter and that's it - tomato sauce kills me in a flare. Other flare foods I can eat are plain rice, plain skins-off potatoes (or also with a little butter), hard-boiled eggs, plain white bread or plain flour tortillas, baked chicken. If the flare isn't too bad I can get away with a tuna sandwich (canned tuna, mayo, white bread) and fried rice is usually pretty safe too (white rice, soy sauce, egg).
And for some reason I also can and do eat potato chips - I've been told that my sodium levels are low, most likely due to having a lot of d when I'm flaring, so my body craves salty things like chips in a flare. Pringles are the only chips I've found so far that I can't eat in a flare - for some reason, they seem to tear up my guts, must be the sharp edges? I usually eat Ruffles and those don't cause pain. I'll have to try Sun Chips next time and see if they help.