Bring a pot of salted water to a rolling boil and cook the broad beans for about 3 minutes, until tender but al dente. Remove and drain. When they are cool enough to handle, peel away their thickish membrane and, using a paring knife, cut away the black eye on the side of the bean. Place the beans in a serving bowl.

Core the tomatoes and cut them into ½-inch dice. You can choose to peel them if you like by scoring the bottom with a sharp paring knife and blanching them for a few seconds. Drain, cool and peel off the skin. Dice the skinned tomatoes as you would an unskinned one. Add the diced tomatoes to the broad beans.

Peel, halve and dice the onion. Mince the garlic. Add these to the bean bowl, too. Add the fresh mint and lemon zest. Whisk together the lemon juice and olive oil, season with a generous pinch of salt, and dress the salad with the lemon vinaigrette.

Serve.