In a small bowl, combine the 3 tablespoons olive oil, the sherry vinegar, garlic and a pinch of salt. Set aside.
Heat a gas grill to medium or a broiler to high. Brush the bread generously with olive oil on both sides and sprinkle with salt. Put the slices directly on the grill grate or a few inches under the broiler element and cook until a light golden brown on the first side, about 1 minute. Flip and cook for 1 minute more until the other side is golden. Transfer the bread to a cutting board and cut into 3/4-inch cubes.
Cut the tomatoes into pieces all about the same size. (A rough guideline: Cut large tomatoes into 1-inch pieces; medium tomatoes into wedges; small tomatoes into quarters; very small tomatoes in half.) Peel the cucumber, trim the ends and cut it in half lengthwise. Scoop the seeds out with a spoon. Cut each piece in half again lengthwise (so that you have 4 long pieces); cut the pieces crosswise into 1/2-inch slices.
In a large mixing bowl, combine the tomatoes, cucumbers, feta, olives, scallions, 1/4 teaspoon salt, a few grinds of fresh pepper and half of the herbs. Add the bread pieces and toss gently to combine. Drizzle the olive oil vinegar mixture over the salad and toss gently but thoroughly. Taste for salt and pepper. Let sit for 5 to 15 minutes to let the bread absorb some of the tomato juices, tossing once or twice. Turn out into a pretty, shallow serving bowl and garnish with the remaining herbs.
Recipe by Susie Middleton, author, Fresh from the Farm: A Year of Recipes and Stories
Copyright Susie Middleton from Fresh from the Farm: A Year of Recipes and Stories (Taunton Press, 2014). Visit Susie at SixBurnerSue.com.