Pineapple.
Let the qualities of that fruit pop into your thoughts. It's sweet. It's juicy. It has that tangy bite common to citrus. It's usually paired with dessert items, tropical drinks and candies. But pineapple has another, somewhat contentious application: Pizza. Yes, the infamous Hawaiian Pizza, a classic pie of chewy dough, rich tomato sauce and gooey cheese topped with ham and pineapple. It seems wrong, such a sweet, sunny flavor pairing with the savory notes of that Italian dish, but its supporters can tell you that it works surprisingly well. The sweetness and the acidity of the pineapple mix with its companion notes in the tomato sauce while putting some extra life into the already rich cheese. Taking some cues from the unintuitive genius of pineapple on pizza, consider some of these other, unusual toppings.
Pickles
Pickled vegetables don't get enough love for how versatile they truly are. While few pizza restaurants offer pickles as a topping, there's really no reason why they should skip this common delicacy. After all, pickled peppers stray awfully close to the average pie, either as peperoncini or as banana peppers. The only real difference between pickled peppers and classic cucumber pickles is that the former distract from the strong vinegar taste with pure heat. A softer, milder pickle slice adds a certain top note to the taste of pizza that is unexpected but actually rather pleasant.
Plantains
Fried plantains, to be specific. With more body and less sugar than its cousin the banana, the plantain is featured far too rarely in international cuisine. Perhaps this is because plantain slices are work-intensive or because the fruit is rarely imported to the average grocery store, but we're working in hypotheticals here anyway. Plantains give pizza some extra body without dominating the flavor profile. They're a nice alternative to strong, salty toppings like pepperoni.
Asparagus
This one works especially well on white pizza, the gourmet variety of pie that uses Alfredo sauce rather than red sauce. Fresh, firm asparagus sliced long-ways provides a nice contrast to the chewy yield of pizza while adding a certain freshness and, for lack of a better term, green-ness to the flavor.
Crab
Seafood doesn't get enough love in pizza as far as I'm concerned. Crab is the perfect candidate because it's not too moist, as clams tend to be, nor is it too rich and expensive like lobster. Crab also has a milder, sweeter flavor than shrimp while also tending to be softer, meaning that it will come away in a single bite without any problem.
Lettuce
Too often we forget that pizza topping don't need to be cooked with the pie. Cool, fresh toppings added just before eating can be truly delightful, as with crisp lettuce. The extra crunch and pleasant roughage of lettuce has long been a companion to pizza as salad. Why not just add it to the top of the pizza itself?