Jax Brewery is a place in the French Quarter, near and I assume named for Jackson Square. It was originally, obviously, where they made Jax beer, but by the time I moved to New Orleans, it was a touristy shopping center. Upstairs is the Bayou Country store, as touristy as you can imagine, with alligator skulls on the wall, and talking Cajuns-in-your-pocket, and all sorts of knick-knack tchotchke crap. But they also made the best pralines I've had, and had one of those big Walls Of Hot Sauce, with a rotating assortment of sauces you could sample on pieces of popcorn. We used to go in pretty often and try whatever the new samples were.
One of the things we bought as a result of sampling it was this stuff called Banana Ketchup. Banana ketchup is actually a fairly common Filipino sauce, but this brand wasn't Filipino, I forget where it was from. It didn't taste very banana-ey, but when you think about it, Heinz doesn't taste very tomatoey. The banana ketchup was great with chicken -- sort of similar to, but not mistakeable for, barbecue sauce.
Ketchup has become synonymous with tomato ketchup, though walnut ketchup and mushroom ketchup were originally much more common, and predate the tomato version by a century or so. I suspect the visual appeal, the umami notes, and the timing of the popularity of hamburgers and hot dogs have something to do with tomato ketchup's ascent in North America, but I'm no food historian, that's just a roundabout guess. I'm not sure you could come up with a formal definition of ketchup that would include all the non-tomato variants while excluding all those things that don't call themselves ketchup, but food tends to be that way. The main thing is, when you hear "such-and-such ketchup," I think what you expect, and what you ought to expect, is a viscous homogeneous sauce with a little vinegar tang and a little spice. (You don't think of tomato ketchup as having any spices because you think of it as ketchup-flavored, but the little bit of spicing they add is key.)
This was all on my mind today when I made macaroni and cheese. Apparently Canadians often put ketchup on theirs. I'm not Canadian, but I am pretty far north. I usually put hot sauce on my mac and cheese.
Four-cheese macaroni: bechamel sauce (with a little cornstarch and dry mustard), cooked penne (Trader Joe's "pennette"), Gruyere, aged Gouda, Pecorino Romano, cheese curds; baked with breadcrumbs on top.
Three-pepper ketchup: pickled cherry peppers, roasted piquillo peppers, Hungarian paprikash paste, boiled celery root, a little Spanish smoked paprika, a little allspice, a little thyme; pureed, strained, and squirted out of a sriracha bottle.