A couple other possible inclusions:
Mealworms, crickets or any other ‘bug’ that’s regularly eaten (yes, the maggot cheese covers this, but make it explicit). Defense Department Research should be able to develop a method of live-storage for this dish.
Don’t forget to include at least some wheat, peanuts, soy, and tree nuts, preferably in a fine powder mixed into every dish (not so much ‘offensive’ as ‘makes certain people unable to eat it’) Oh, and put some animal-derived gelatin in the powder, too, for both offensive ingredients and offensive texture. Naturally, these ingredients all come from genetically modified organisms.
Soy-based fake meat (but with animal gelatin). Or tofu, but not in a tofu dish, but just substituted in for a real flavorful meat (tofu reuben or something).
I know swastika-shaped cookies and what-not are out, but would something like hamentashen (regularly made, but very much associated with a particular religious tradition) count? In the case of Hamentashen, make them sweet but bacon-cheese flavored, just to offend a) kosher Jews and halal Muslims, b) those opposed to Jews, and c) those opposed to savory-flavored desserts. Obviously the proper method is some combination of actual non-kosher bacon and offensively bad, probably carcinogenic artificial bacon flavor.
Have ‘fries’. The word before “fries” should be “French”, but covered with a sticker saying “Freedom”, and with the sticker having a marker crossing it out and writing “French” back in. That should offend people on both sides of the issue.
I suppose if you can label dishes “authentic” <whatever> then there are lots of possibilities. “Authentic southern cornbread” that’s as sweet as a dessert, ‘Authentic New England Clam Chowder” that’s tomato based, that sort of thing.