1 (20-ounce) can pineapple chunks in 100% pineapple juice
3 tablespoons dark or light brown sugar
3 tablespoons soy sauce or tamari
2 tablespoons finely chopped garlic
2 tablespoons finely chopped fresh ginger
1 tablespoon tomato paste
1 1/2 pounds boneless, skinless chicken breast, cut into 1-inch pieces
1/2 teaspoon freshly ground black pepper
2 teaspoons kosher salt, divided
1/4 cup cornstarch
1/4 cup canola or vegetable oil
1 medium red onion, sliced lengthwise
1 medium red bell pepper, stemmed, seeded, and sliced
Open the can of pineapple chunks and drain 1/2 cup of the pineapple juice into a measuring cup. Discard or reserve the remaining juice for another use. Reserve the pineapple chunks in the can. Add the brown sugar, soy sauce, garlic, ginger, and tomato paste to the juice in the measuring cup and whisk to combine. Set aside.
Pat the chicken dry and place it in a medium bowl. Sprinkle it with the pepper and 1 1/2 teaspoons of the salt and toss to coat. Sprinkle with the cornstarch; toss again to fully coat.
Heat the oil in a large skillet over high heat. Shake the excess cornstarch from the chicken and add it in a single layer to the skillet. Cook, undisturbed, until golden brown on the first side, about 3 minutes. Flip the chicken and cook, stirring occasionally, until browned on all sides, 2 to 3 more minutes.
Add the onion and bell pepper and cook, stirring often, until starting to soften, about 3 minutes. Add the pineapple juice mixture and cook, stirring occasionally, until it starts to thicken, about 1 minute. Add the reserved pineapple chunks and remaining 1/2 teaspoon salt, stir until incorporated, about 1 minute. Serve over cooked rice.
