Bring a saucepan of water to a boil. Fill a bowl with ice water. Cut a slit into the base of each tomato and blanch them in the boiling water until their skins start to split, about 15 seconds. Using a slotted spoon, transfer the tomatoes to the ice water to cool, then drain and peel.

In the same water, cook the fava beans until just tender, 2 minutes. Remove and let cool slightly, then peel. Blanch the peas until just tender, 2 minutes. Drain well.

In a medium bowl, whisk 3 tablespoons of the olive oil with the lemon juice and season with salt. With a paring knife, trim the artichoke stems and snap off the tough outer leaves until you reach the light green inner leaves. Using a serrated knife, cut off the top third of the artichokes. Trim the bottoms and stems. Cut the artichokes in half lengthwise. Using a teaspoon, remove the chokes, if any. Thinly slice the artichokes lengthwise, add them to the dressing and toss to coat. Add the peeled tomatoes and the fava beans and toss again.

In a medium skillet, heat 1 1/2 teaspoons of the olive oil. Add the radishes and cook over moderate heat, stirring occasionally, until tender, about 2 minutes. Add the blanched peas and cook, stirring, for 1 minute. Season with salt.

In a medium bowl, toss the watercress with the remaining 1 1/2 teaspoons of olive oil and the lemon zest and transfer to plates. Top with the artichoke salad and the radishes and peas; serve.