1/2 cup extra-virgin olive oil, divided
2 cloves garlic, grated on a microplane grater
1 small onion, finely sliced (about 1 cup)
1 teaspoon dried oregano
1/2 teaspoon red pepper flakes
2 slices white bread, crusts removed, torn into rough 1/2-inch pieces
2 (28-ounce) cans whole peeled tomatoes packed in juice
Kosher salt and freshly ground black pepper
Minced chives, basil, or parsley as garnish
Toasted bread or grilled cheese for serving