Cook orzo in water to al dente, according to package instructions.
While orzo is cooking, heat a large skillet with oil and lightly sauté shrimp. Remove shrimp from the pan and reserve. Add onions, garlic, and green bell peppers and cook until lightly golden. Add spices and cook for 1 minute. Stir in tomatoes and water and simmer for 1-2 minutes.
When orzo is ready, drain and stir in along with cooked lentils and shrimp into the skillet. Simmer for 2-3 minutes. Season with salt and pepper to taste, garnish with green onions and serve.