Step 1

Heat 2 tablespoons of the oil in a heavy large saucepan over medium heat. Add the shrimp and sprinkle with 1/2 teaspoon of the salt and 1/4 teaspoon of the pepper. Cook until the shrimp are just opaque in the center, about 3 minutes. Remove the pan from the heat. Transfer the shrimp and juices to a bowl to cool.

Step 2

Add the remaining 3 tablespoons oil to the pan. Add the fennel and onions. Cook until tender, about 4 minutes. Add the garlic and cook until aromatic, 30 seconds. Add the rice. Stir until well coated and translucent in spots, about 2 minutes. Add the wine. Cook until the wine is absorbed, stirring often, about 2 minutes. Add the broth, lemon juice, zest, and the remaining 1 1/2 teaspoons salt and 1/4 teaspoon pepper. Increase the heat and bring to a boil, stirring often. Reduce the heat to medium-low. Simmer until the rice is just tender but still has some bite and the risotto is creamy, stirring often, 13 to 14 minutes.

Step 3

Mix in the arugula. Stir until the arugula wilts, about 30 seconds. Add the shrimp. Mix in additional broth if needed, 1/4 cup at a time, until the risotto is creamy.

Step 4

Spoon the risotto into 4 shallow soup bowls.