1. For each flatbread, heat grill-pan over medium-high heat. Roll out 3-oz. dough into 7-inch round; lightly oil one side of dough and sprinkle lightly with kosher salt. Place on hot grill pan, oiled-side down. Cook until browned on bottom side; flip and cook other side, 4 to 5 minutes. Transfer pizza to warm oven (225 F.) and hold until ready to serve.
2. Combine salad greens, chopped herbs and green onions; set aside.
3. For dressing, combine lemon juice, mustard and olive oil. Toss salad mixture with dressing. Season salad with kosher salt and pepper; add more to taste if necessary.
4. For each serving, cut one grilled flatbread into quarters. Plate the pieces, spoke-fashion, leaving plate center clear. Add 1 cup salad to center of plate; top with slivered oven-roasted tomatoes and cheese cubes.

Oven-Roasted Tomatoes: Cut 2 large plum tomatoes vertically into 4 slices each. Arrange single layer on wire rack set in roasting pan. Sprinkle tomatoes lightly with coarse salt and black pepper. Drizzle lightly with olive oil. Bake in 300 F. oven until slices are shriveled slightly but retain some moisture, about 1 hour.