Wash the limes hot, rub dry and finely grate the peel. Cut off the rest of the peel all around with a knife so that the white skin is completely removed. Quarter limes lengthwise.
Onions peel and chop finely. Wash the garlic cloves. Heat 40 g fat in a pot and fry onions and garlic. Add rice, fry and season with a little salt and pepper. Add lime zest.
Pour in some stock and wine. Add a little bit each time as soon as the liquid has been absorbed by the rice. Stir from time to time. Wash the mussels thoroughly and remove any mussels that are already open.
Halve the shrimps with skin lengthwise and remove the black intestine. Wash and drain the prawns. Wash squid tubes and cut them into rings. Pour the remaining stock and wine (approx. 1/4 litre) into the rice after approx. 15 minutes.
Fold in the mussels and lime quarters. Cover and cook for about 15 minutes until the rice has absorbed all the liquid. Heat the remaining fat in a frying pan and fry the prawns for approx. 3 minutes.
Season with salt and pepper, take out and keep warm. Turn squid rings in the flour and fry them in the frying fat for 2-3 minutes and season. Fold the Parmesan cheese into the risotto and serve with squid rings and prawns.
Garnish with lime zest as desired. Do not eat mussels that have not yet been opened after cooking.