Drain the tomatoes in a colander over a bowl, reserving the tomato liquid. Coarsely chop the tomatoes. Add 3/4 cup of the chicken stock to the tomato liquid.
Heat a medium-sized saucepan over medium-high heat for the risotto. Add 1 tablespoon of olive oil to the pan and swirl.
Add the rice and stir to toast, about 2 minutes. Add 1/2 cup of the onion and 2 of the garlic cloves. Stir until translucent.
Add 2 cups of the stock. Bring it to an immediate boil, then reduce to a simmer. Cook for about 15 minutes on the lowest possible heat setting.
Now, you should be able to get the rest of the dish ready while the rice is cooking. Let's go.
In another skillet, heat the other tablespoon of olive oil. Medium heat.
Add the fennel bulb, 1/2 cup of the onion, and 2 cloves of garlic. Stir to brown gently.
Add the tomatoes, the crushed red pepper, and the minced chiles. Sauté and stir for about 4 minutes.
Add a few tablespoons of the reserved tomato juice mixture and 1/4 cup stock to moisten. Fold in the lobster, reduce heat to low, and warm the lobster chunks through, about 2 minutes.
Now, return your attention to the risotto. It's time to stir and gradually add liquid, one ladleful of the remaining tomato juice mixture at a time. Stir until quite creamy, but still toothsome. Add the butter and salt, and stir to finish.
Serve the risotto in shallow bowls, with a generous spoonful of the lobster ragout on top.