Clean the shrimps and toss the heads and shells in the warm vegetable stock, together with a couple of mint sprigs to give it more flavour.
Chop the shrimps and put in a bowl with the lime juice, olive oil, salt, ground pepper and the finely chopped mint. Cover and set aside in the fridge to marinate for at least 10 minutes.
In a large pan, drizzle the olive oil, add the finely chopped shallot and let it sweat. Add the rice and toast for a couple of minutes, then pour the white wine and let it evaporate.
Add the warm stock to the rice, a couple of ladles at a time, letting it absorb it before adding more.
When the rice is almost cooked, add the shrimps and cook for another minute.
Turn off the heat and add a tablespoon of butter to stir in the risotto until creamy.