Grilled Tomato and Fennel Salad

2 fennel bulbs, sliced

2 leeks, cut in half lengthwise

4 cups San Marzano or large cherry tomatoes, quartered

1/4 cup rice vinegar

2 tablespoons whole-grain mustard

1/2 cup oil, plus more for grill pan (if needed)

2 ounces crumbled feta

1/4 cup chopped mint

Salt and pepper

Heat a grill or grill pan on medium until just smoking. Oil grill pan, if using. Add fennel and leek and grill until marked, about 2 minutes per side. Transfer to cutting board. Grill tomatoes until marked, about 2 minutes. Transfer to bowl. When leeks and fennel are cool enough to handle, cut them into small pieces and add to tomatoes. Season with salt and pepper. In a small bowl, whisk together vinegar and mustard, then whisk in oil. Add to vegetables, toss, then toss in feta and mint. Serve immediately.