Step 2

Prepare grill for cooking. If using a charcoal grill, open vents on bottom of grill.

Step 5

Make dressing:Whisk together zest, lemon juice, shallot, mustard, and salt in a small bowl. Add oil in a slow stream, whisking until dressing is emulsified. Whisk in pepper and parsley.

Step 8

Grill zucchini: Lightly brush zucchini all over with oil. When fire is hot (you can hold your hand 5 inches above rack for 1 to 2 seconds), grill zucchini, cut sides down first, on lightly oiled grill rack, uncovered, turning once, until zucchini are just tender, 8 to 12 minutes total. Transfer to a cutting board and cool slightly, then cut diagonally into 1/2-inch-thick slices.

Step 11

Toss zucchini with purslane, tomatoes, and dressing in a large bowl. Serve immediately.