Zucchini Panzanella

Recipe adapted from Eric Kim

3 medium zucchini (about 1 pound), trimmed
Kosher salt (Diamond Crystal) and black pepper
2 packed cups (½-inch) cubes of dense, chewy, day-old bread (5 ounces), such as sourdough
4 tablespoons olive oil
1 bunch scallions, thinly sliced at an angle (about 2 cups)
1 teaspoon dried oregano
1 tablespoon plus 2 teaspoons maple syrup
1 large garlic clove, finely grated
1 tablespoon plus 1 teaspoon rice vinegar
2 teaspoons Dijon mustard
½ cup Castelvetrano or other green olives, pitted and torn into halves
1 packed cup fresh flat-leaf parsley leaves and tender stems

Slice 1 zucchini crosswise into ¼-inch-thick coins. Slice the remaining 2 zucchini crosswise into 2-inch-long segments; press on each segment with your hand (and body weight) to crush so the two rounded sides are flattened, then tear into bite-size pieces. Add all of the zucchini to a large colander set in the sink, sprinkle with 1 teaspoon salt and toss. Let sit to drain, about 30 minutes.
While the zucchini drains, heat a large skillet over medium. Add the bread and toss frequently with a wooden spoon until lightly browned and beginning to dry out, about 5 minutes. Add 2 tablespoons oil, the scallions and ½ teaspoon dried oregano, and toss until the bread is evenly coated. Season to taste with salt and pepper, and cook, stirring occasionally, until the bread is crispy and evenly browned, 5 to 7 minutes. The scallions should be slightly wilted and browned.
Add 1 tablespoon maple syrup to the pan. Toss frequently until the bread is evenly coated and the syrup has caramelized, 2 to 3 minutes. Take the pan off the heat and set aside so the croutons can cool slightly while you finish the salad.
In a large bowl, whisk together the garlic, vinegar, mustard and ½ teaspoon each salt and pepper with the remaining 2 tablespoons olive oil, 2 teaspoons maple syrup and ½ teaspoon oregano.
Transfer the drained zucchini to a clean kitchen towel and blot dry. Add to the bowl with the dressing and toss. Transfer the croutons to the bowl, along with the olives and parsley, and gently toss to coat. Adjust seasoning with salt and pepper, and serve immediately.