Marinate the shrimp and pork loin with the fish sauce and MSG in a glass or ceramic bowl for 30 minutes.
Mix rice flour, water, coconut milk, green onions, and saffron powder.
Heat 1 tablespoon vegetable oil in a pan over medium-high heat. Drop 1/4 of the rice flour mixture and fry a large, thin pancake until bubbles form and the edges are dry, 3 to 4 minutes.. Put 1/4 of the shrimp and pork mixture on the pancake. Reduce heat to medium, add 1/4 of the bean sprouts and basil, flip, and cook until browned on the other side, 2 to 3 minutes. Fold pancake in half and transfer to a plate. Repeat with remaining batter and filling.
Mix lime juice, fish sauce, water, sugar, red chiles, garlic, and MSG for sauce together. To eat, roll the pancakes up together in a mustard green leaf and dip in the sauce.