Step 1

• Place a foil-lined baking sheet on top rack (for 4 servings, use 2 foil-lined sheets on top and middle racks) and preheat oven to 450 degrees. Wash and dry produce. • Halve, peel, and thinly slice onion. Drain pineapple over a small bowl, reserving juice. Stir 1/4 of the onion, half the vinegar (you’ll use the rest later), and a pinch of salt into bowl with juice. Set aside.

Step 2

• Heat a drizzle of oil in a large pan over medium heat. Add remaining onion; cook, stirring and adding splashes of water as needed to prevent sticking, until softened, 6-8 minutes.

Step 3

• While onion cooks, halve, core, and very thinly slice green pepper into strips. Toss in a second small bowl with a drizzle of olive oil, salt, and pepper. Dice mozzarella into 1/2-inch pieces. Pat chicken dry with paper towels; season all over with salt and pepper. Heat a drizzle of oil in a second large pan over medium-high heat. Add chicken; cook, stirring occasionally, until cooked through, 4-6 minutes.

Step 4

• Once cooked onion is softened, increase heat under pan to medium high. Add pineapple and a drizzle of oil; cook, stirring, until pineapple is lightly browned, 2-3 minutes. • Stir in remaining vinegar. Cook, stirring, until onion and pineapple are caramelized and jammy, 1-2 minutes more. Turn off heat and season with salt and pepper.

Step 5

• Brush or rub each flatbread with a drizzle of oil. Remove prepared baking sheet from oven; carefully place flatbreads on sheet. (For 4 servings, divide flatbreads between both prepared sheets.) • Evenly spread flatbreads with BBQ sauce, then top with caramelized onion and pineapple, green pepper, Monterey Jack, and mozzarella. Add chicken to flatbreads.

Step 6

• Return flatbreads to top rack until cheese melts and edges are golden brown, 10-12 minutes. (For 4 servings, return to top and middle racks; swap rack positions halfway through baking.) • Transfer flatbreads to a cutting board and top with pickled onion (draining first) to taste. Slice into quarters, divide between plates, and serve. Chicken is fully cooked when internal temperature reaches 165°.