Whisk the lime juice, sugar, chile paste, and fish sauce in a bowl until the sugar dissolves. Add the peanuts and cilantro and stir until evenly dressed with the sauce.
When ready to serve, arrange the lettuce leaves on a large platter. Put about 14 cup of pineapple in each leaf and season with salt to taste. Top the pineapple with the nut mixture. Serve, letting your guests wrap (or fold) each lettuce leaf to enclose the filling.
Sambals are potent Indonesian condiments packed with chiles. There are different kinds, but the slightly tangy sambal oelek is a blend of hot red chiles, salt, vinegar or tamarind, and sometimes garlic. Other Asian chile pastes are suitable substitutes. It is important to chop the nuts by hand-not in a food processor. Machine-chopped nuts will be overworked and pasty. The dish is so much better when the nuts have a distinct texture.