Flavor – Oniony coleslaw

Cauliflower fritters. Mix some egg, ice-cold water and flour, then stir in the other ingredients. Gently put about one or two tablespoons at a time into a deep-fryer using two spoons. We do something similar to make "kaki-age", which is a mix of vegetables prepared using a batter similar to tempura, and generally includes onion. You can probably also get away with doing this in a frying pan with just the bottom covered in oil if you keep the oil temperature stable enough.

For what it's worth, I prefer to make mashed potatoes by ricing them then adding butter, milk, scallions and cream then letting them roast for a while in an enameled cast-iron pot. I've never noticed an unpleasantly raw taste with the scallions in this way. Perhaps a similar approach would work for the cauliflower.

I don't think there's any dairy in twinkies or similar packaged items -- it's whipped fat, with sugar and flavorings.

But all of the items you mention contain fat, so it's possible that it's a product of rancidity.

I don't know if it's related to the supertasters stuff that bikeboy389 mentioned, but some people experience taste differently -- I can't stand bitter flavors (about 1/2 the items on the list mentioned, especially coffee, artificial sweeteners and all hopped beers), but I love sour; much more so than most other people. People also smell differently (eg, the issue with asparagus, although that one's an issue not just with sensing it), so it's possible that you're just more sensitive to taste/smells in general, or to a specific chemical compound than others.