Preheat broiler to 400°F | 205°C. Line a baking sheet with parchment or a Silpat mat.
Drizzle 2 tablespoons olive oil over bread cubes and toss to coat. Sprinkle lightly with salt. Place bread cubes on prepared baking sheet under broiler, about 8-inches from the heat. (Not the closest rack to the element.) Leave the door open and keep an eye on them. When you begin to see the bread cube tips turning golden, take them out. This should take about 3 minutes or less. Using a spatula or tongs, toss the cubes again and put them back into the oven. Continue to toast until they are gently toasted thorough: about another 3 minutes. When bread cubes are toasted, remove from baking sheet and set aside. Preheat oven to 400°F | 205°C.
Roast Vegetables
In a large bowl, combine sliced onion, eggplants, squash and half of the sliced tomatoes. (Reserve the other half of the tomatoes for later.) Drizzle 2 tablespoons each olive oil and balsamic vinegar over vegetables. Sprinkle with salt and pepper and toss to coat.
Pour vegetables onto baking sheet and shake the sheet gently to distribute them evenly.
Bake in preheated oven [400°F | 205°C] for 25-30 minutes, until eggplants are completely cooked.
Make Dressing
Spoon out ½ cup of the tomatoes from the roasted vegetables on the baking sheet. Allow the rest of the roasted veggies to cool slightly while you proceed.
In a blender cup, combine the ½ cup of roasted tomatoes, chopped garlic, 2 tablespoons each balsamic vinegar and olive oil. Pulse a few times to combine.
Toss & Serve
In a large bowl, combine chopped romaine, toasted bread cubes, remaining tomato halves, cucumber, roasted vegetables, feta, fresh herbs, and balsamic tomato dressing. Toss gently to coat. Allow to chill for up to 2 hours before serving. Toss once more before serving and garnish with additional crumbled feta.
Notes
The recipe is quite flexible: you can vary the veggies to suit your tastes or your garden's bounty.