Prepare components: Dice chicken into 1-inch pieces and pat thoroughly dry with paper towels. In a small bowl, whisk together the reserved 1/4 cup pineapple juice, soy sauce, brown sugar, minced garlic, minced ginger, and smoked paprika. In a separate tiny bowl, mix the cornstarch with 1 tablespoon of cold water to create a slurry.

Sear the chicken: Heat oil in a large skillet over medium-high heat. Once shimmering, add chicken in a single layer, being careful not to overcrowd the pan (work in batches if needed). Cook undisturbed for 3-4 minutes until a deep golden-brown crust forms. Flip and cook for another 2-3 minutes until cooked through. Remove chicken from the skillet and set aside.

Caramelize the pineapple: Add the drained pineapple chunks to the same hot skillet. Cook for 2-3 minutes, stirring occasionally, until the edges begin to brown and caramelize.

Combine and thicken sauce: Return the seared chicken to the skillet with the pineapple. Pour the prepared sauce mixture over everything and bring to a simmer for 1 minute, allowing flavors to meld. Give the cornstarch slurry a quick re-whisk and pour it into the pan, stirring constantly until the sauce thickens almost instantly into a glossy glaze that coats everything.

Assemble and serve: Warm the tortillas by charring them lightly over a gas flame or heating in a dry pan. Spoon a generous amount of the pineapple chicken filling into each tortilla. Top with a crunchy slaw, a sprinkle of fresh cilantro, and a squeeze of fresh lime juice. Serve immediately.