Combine 3 cups cooked brown rice with 2 tablespoons lemon juice. Cook 1 pound peeled, deveined shrimp in 2 batches in a nonstick skillet over medium heat using 1/2 tablespoon oil for each batch, until shrimp are pink, 3-4 minutes. Transfer to a plate. Add 1 seeded, sliced Thai red chile pepper, 1/4 cup chopped lemongrass, 1 tablespoon chopped ginger, 1/2 cup sliced red onion, and 3 tablespoons sugar to pan and cook, 1 minute. Add 1 1/2 tablespoons fish sauce and 1 cup coconut water; cook 2 minutes. Add shrimp to pan; cook 2 minutes. Divide rice and shrimp among 4 bowls; garnish with cilantro and mung bean sprouts.