For the shrimp: In a wok or large skillet, heat the oil over medium-high heat until shimmering-hot. Add the garlic and chili powder and cook, stirring, until fragrant, less than 1 minute. Add the shrimp in an even layer and season with a pinch of salt. Cook, turning once, until the shrimp are lightly browned and almost cooked through, but still slightly translucent, 2 to 3 minutes total. Transfer the shrimp to a plate and wipe out the wok with a paper towel. Place a measuring cup with 1⁄4 cup water next to your cooktop. Set the wok over medium heat and add the brown sugar, lime juice (this helps keep the sugar from crystallizing) and 2 tablespoons water. Cook, stirring often, until the sugar turns into an amber-colored caramel (it should be as thick as honey), 6 to 7 minutes. Then, stir in the fish sauce and soy sauce and remove from the heat. Once a smooth sticky sauce forms (about as thick as honey), after 30 seconds or so, add the cooked shrimp, scallions and scallions, toss to coat.
Assemble the lettuce wraps: Remove the Quick Pickles (see recipe below) from the fridge and arrange the lettuce leaves, cucumber and cilantro on a serving platter. To serve, spoon some of the shrimp onto a lettuce leaf along with some rice (if using) and top with a few pickles, cucumber and a sprig of cilantro. Roll up and eat immediately.
Yield:Makes about 1 cup
In a medium bowl, combine the vinegar water, sugar and 2 pinches of salt and stir until the sugar is dissolved. Add the carrot and radishes and toss to combine. Transfer to the fridge to chill for at least 20 minutes.