At first I thought it was a Burger Quiz reference (french TV show with teams "Mayo" and "Ketchup"), but no. ^^'

Some variants of the beef stroganoff use ketchup. It is relatively common in the Brazilian version.

I'm genuinely surprised it wasn't Ketchup and Mustard. I like Mayo as much as the next person, but you typically don't think of it in relation to the other two.

Ketchup can be used for Rosé sauce, which goes well with some snacks like breaded crab legs, saldas, or chicken nuggets, for example

Is that morgan playing splatoon and getting lueded?! :O

I just mix mayo with ketchup.

You plebs and your inferior condiments!
*laughs in Heinz 57*

Yup, don't know what mouraisu is.

And I guess salad dressing counts but you are also using mayo for it so...

IIRC thousand island dressing was made of ketchup and mayo, so there's one. Plus omurice as ms. Litvyak mentions.

You can use ketchup to make sweet and sour sauce.

Jo doesn't know of grorious omuraisu? Shamefur dispray!