Step 1

Combine vinegar, brown sugar, ketchup, chili flakes, and water in a small saucepan and bring to a simmer over medium-high heat, whisking to combine until sugar is dissolved. Combine remaining tablespoon water and corn starch in a small bowl and whisk with a fork to form a slurry. Whisk into sauce and bring to a boil. Allow to cool while you form the crab rangoon.

Step 2

Combine cream cheese, crab, and scallions in a medium bowl and fold with a spatula or your hands until combined. Lay one wonton wrapper out on a cutting board (keep the rest under plastic wrap or a damp towel) and place a small amount of filling in the center (about 1 1/2 teaspoons). Moisten the edges with a wet fingertip, the seal by either folding it in have in a triangular shape, or by pushing the four edges in towards the center to create a four-pointed star. Be careful not to allow any air to remain inside as you seal them. Transfer to a large plate, cover loosely with plastic wrap, and repeat until all of the filling is used.

Step 3

To finish the sauce, add pineapple chunks and puree with an immersion blender or by transferring to a standing blender.

Step 4

Heat oil in a wok or Dutch oven to 375°F as registered on an instant read thermometer. Carefully add 10 to 12 crab rangoons to the oil. Cook, adjust flame to maintain temperature and agitating and flipping them constantly with a wire mesh spider until crisp and golden brown, about 3 minutes. Transfer to a paper towel-lined bowl to drain, season with salt, and serve immediately with sweet and sour sauce.