Cook the lobster with your preferred method, then let it cool and separate the flesh from the shells. Set them aside.
Make the Lobster Stock
In a large pot, add a drizzle of olive oil and the roughly chopped onion, garlic, soffritto (onion, celery, carrots), and the tomato paste.
Add the lobster shells and cook for a few minutes, until the vegetables are caramelized. Add the fish stock and simmer for at least fifteen minutes.
Make the Risotto
Finely mince the onion. Drizzle a large pan with olive oil, then sauté the onion, tomato paste, and rice for about 2-3 minutes.
Pour the white wine. Let it evaporate for a couple of minutes.
Add a few ladles of lobster stock, until the rice is covered, and turn down the heat.
Let the rice simmer, mixing it once in a while to make sure it doesn't stick. When the stock is almost completely absorbed, add some more. Continue until the rice is al dente.
About 5 minutes before it's done, add the lobster meat. In the end, the rice should be creamy and not soupy. If there's too much liquid, turn the heat to high and let it evaporate.
When the rice is cooked, turn off the heat and add the butter. Mix well until the butter is fully melted. Serve immediately with freshly chopped parsley.
Notes
For an even more flavorful lobster stock, make it in advance. Simmer covered at low heat for 30 minutes to 1 hour, then turn off the heat and keep it covered for up to two hours, until ready to use.Lobster risotto can be stored in an airtight container in the refrigerator for up to 2 days. The texture may change slightly, but it will still be delicious.