Heat oil in work, add red curry paste and stir to dissolve (about 30 seconds). Add 1/2 cup water and lime leaves or juice. Stir cook about 1 more minute.
Add shrimp, green beans,onion, and sugar, Cook 1 minute on high, stirring. Reduce heat to medium and add the rest of the water. Continue cooking until shrimp and done and beans are hot-crisp, about 3 minutes.
Transfer to serving dish and garnish with red pepper and cilantro.