While you prep your ingredients, toast the walnuts in a dry skillet over medium heat for 3-4 minutes, stirring frequently, until fragrant and lightly golden. Set aside to cool. Meanwhile, chop the lettuce into 1-inch bite-sized pieces, thinly slice the onions into half-moons, dice the pineapples into 1/2-inch chunks, and chop the cilantro. Having everything prepped and ready will make the cooking process smooth and efficient.
Cut the chicken into 1-inch cubes and place in a bowl with the ginger-garlic paste, 1/2 tsp salt, and paprika. Toss well to coat evenly, then let marinate for 1-2 hours at room temperature to allow the flavors to penetrate the meat. I like to marinate while doing other tasks rather than as a separate waiting step—it's the perfect time to prep your other ingredients or get your kitchen organized.
Rinse the marinated chicken under cool water to remove most of the spice coating, then pat dry with paper towels. In a bowl, combine the brown sugar, 3/4 tsp black pepper, and 1/2 tsp salt. Heat a large skillet over medium-high heat and cook the chicken in batches, turning occasionally, until golden brown on all sides and cooked through (about 8-10 minutes total). Once cooked, sprinkle the brown sugar and pepper mixture over the warm chicken and toss to coat lightly, then set aside to cool slightly before dicing.
In a small bowl, whisk together the mayonnaise, lime juice, pineapple juice, 1/2 tsp sugar, 1 tsp honey, and 1/4 tsp salt until smooth and well combined. The dressing should be creamy but pourable—if it's too thick, add a splash more pineapple juice. I find that letting this dressing sit for 5 minutes allows the flavors to meld beautifully, creating a more cohesive tropical taste.
In a large bowl, combine the chopped lettuce, sliced onions, diced pineapples, and toasted walnuts from Step 1. Pour the dressing from Step 4 over the vegetables and toss gently to coat. Add the cooled cooked chicken from Step 3 and fold everything together carefully, being gentle to keep the pineapple chunks intact. Garnish with fresh cilantro just before serving for maximum freshness and aroma.