Whisk the soy sauce, lime juice, brown sugar, and pepper in a small bowl until the sugar is mostly dissolved. Set the sauce aside. Break up any clumps in the cold rice with clean hands or a fork so it will heat evenly.
Heat a large skillet or wok over medium-high heat. Add 1 teaspoon of the oil. Pour in the beaten eggs and gently scramble until just set. Transfer the eggs to a clean plate.
Add the remaining oil to the skillet. Add the onion and cook, stirring often, until it begins to soften. Stir in the garlic and cook just until fragrant.
Add the bell pepper and frozen peas and carrots. Stir-fry until the vegetables are hot and the pepper is crisp-tender. Add the drained pineapple and curry powder, then cook until the pineapple is heated through and has a few lightly golden edges.
Add the cold rice and stir-fry, pressing and tossing to separate the grains. Pour the soy-lime sauce around the edge of the skillet, then toss until the rice is evenly coated and hot.
Return the scrambled egg to the skillet. Stir in the cashews and most of the scallions. Taste and add a little more soy sauce or lime juice if needed.
Spoon into bowls and finish with the remaining scallions, optional cilantro, and lime wedges. Serve right away while the rice is hot and the cashews are crunchy.