Peel and finely chop the onion and 1 garlic clove. Dissolve the stock in 600-700 ml boiling water. Stir in the saffron. Heat 1 tablespoon of oil in a saucepan. Sauté the onion and garlic until transparent. Add the rice and fry for 2-4 minutes until it crackles slightly.
Add wine and bring to the boil. Simmer on low heat until the liquid is absorbed.
Add so much hot broth until the rice is covered. Simmer the risotto open at low heat, stirring occasionally, for a total of 25-30 minutes. Add some stock again and again. Add the frozen peas to the risotto about 10 minutes before the end of the cooking time.
In the meantime peel the shrimps, except for the tail fin. Make a longitudinal incision in the back and pull out the dark gut with a sharp knife. Rinse shrimps cold, dab dry and cut in half lengthwise up to the caudal fin.
Peel and slice the rest of the garlic. Wash the lemon balm and shake dry. Cut leaves into strips. Heat 2 tablespoons of oil in a frying pan. Fry the prawns for about 3 minutes, turning them over.
Fry garlic and lemon balm briefly, season with salt and pepper.
Grate the parmesan finely and fold into the rice with butter. Season to taste with salt and pepper. Serve with prawns.