Two for me: coffee and sushi.
I didn’t start drinking coffee until I was in my middle 20’s. When I tried it as a younger person I didn’t like it because it was so bitter. It wasn’t until I was on a cruise (with my wealthy extended family) I had a fancy boy cappuccino and I was like “hot damn, this bitter water is actually good!” Now I drink at least 4 cups of coffee every moring.
I tried sushi in my teens and absolutely hated it, I remember gagging at the taste of the raw fish. Like coffee it wasn’t until years later as an adult I tried sushi again at a Japanese place in town and I was like “damn, this raw fish is really tasty!” Now sushi is a regular staple takeout food for me.
For me it was a swap out of coffee and tea. I drank tea as a late teenager and early university. But after living in southern Europe for a few months on an internship and getting good espresso, I switched to drinking coffee (also due to getting less sleep in later university). Now my stomach is more sensitive to the tannins in tea, so I can’t drink it unless I ate a meal very recently, or else I get nauseous.
Also beer. obviously didn’t really drink it as a child other than grandparents offering me a sip, but even when I started drinking, didn’t like the hoppiness and preferred wine at first. But after a friend getting me into brewing and finding Belgian beers I am a real beer aficionado.
And also rosemary. Didn’t really hate it, but also didn’t like it when it was in food. But my grandmother made good rosemary bread at some point and now I always associate it with her. Which out of some form of irony a few months later my grandmother stopped baking with rosemary, because she got violently ill after eating rosemary bread (unrelated) and now has a disgust reaction to rosemary.