Heat a large, nonstick skillet or a large wok over medium-high heat until a drop of water evaporates immediately upon contact. Add the oil, carrot, and shrimp. Stir-fry about 2 minutes, until shrimp is pink and opaque. Stir in the garlic, and cook 15-30 seconds, until golden. Fold in the cooked rice, and stir-fry for 2 minutes: scoop rice up, press into the pan, and scoop up again. Fold in the scallions and fish sauce and cook for just 30 seconds. Transfer to a serving dish. Top with chopped cilantro and serve hot, with cucumber slices and lime wedges.