In a medium bowl combine brown sugar, corn starch and salt. Whisk in pineapple liquid, vinegar, water, soy sauce until smooth.
Heat a wok over medium high heat. Add oil and heat until the oil shimmers. Add meat and sprinkle with paprika and sear. Cover and cook about 20-25 minutes, or until tender, stirring occasionally. Add garlic and ginger, and stir-fry for 3 to 4 minutes until garlic is fragrant. Gradually stir cornstarch mixture into meat.
Reduce heat to medium and simmer until thick, stirring constantly. Stir in pineapple. Cover and simmer 3 to 4 minutes or until pineapple is tender. Serve with hot steamed rice. Makes 4 servings.