Peel the skin of daikon radishes and slice julienne cut. In a pot, add 600 ml water and bring to a boil. Add daikon radishes and cook 2 minutes. Drain and set aside.
Cut the heads from the shrimps and rinse. Remove shell and deveine the prawns. Rinse and set aside.
Heat the wok over high heat, add vegetable oil, ginger and green onions and stir fry for 1 minute. Add julienne daikon radishes, stir for 1 minute. Add chicken broth, 300 ml water, salt and pepper. Cook for 5 minutes. Add prawn heads and cook for 5 minutes. Add prawns and cook 2 minutes more. Add MSG to taste.
Remove prawn heads and ginger from the soup before serving.