Prepare the shrimp-vegetable sauce:

Bring a small saucepan of water to a boil. Blanch the zucchini for about 1 minute. Drain and set aside.

Heat the oil in a large nonstick skillet over medium-high heat. Add the garlic and cook just long enough to flavor the oil, about 1 minute. Discard the garlic and add the shrimp. Cook, stirring, until the shrimp begins to color, 1 to 2 minutes. With a slotted spoon, transfer to a bowl.

Return the skillet to medium-high heat and add the tomatoes. Cook, stirring a few times, until the tomatoes are soft and the juices have thickened, 2 to 3 minutes. And the reserved zucchini and shrimp, Stir once or twice, season lightly with salt and pepper, and turn off the heat.

Prepare the risotto:

Heat the broth in a medium saucepan and keep warm over low heat.

Melt 3 tablespoons of butter in a large, heavy skillet over medium heat. When the butter foams, add the onion and cook, stirring until pale yellow and soft, 4 to 5 minutes. Add the rice and stir until it is well coated with the butter and onion, and begins to whiten, about 2 minutes. Stir in the wine. When the wine is almost all evaporated, add 1 cup of the hot broth, and stir until most of the broth has been absorbed. Continue cooking and stirring the rice in this manner, adding 1 cup of broth at a time, for about 16 minutes.

Add the shrimp-vegetable mixture and stir until most of the liquid has been absorbed, 2 to 3 minutes. At this point the rice should be tender but still firm to the bite.

Add the remaing tablespoon of butter and stir for about 1 minute, until the rice has a moist, creamy consistency. Taste, adjust the seasoning and serve.