Ingredients
2 to 3 tablespoons olive oil, plus more for greasing
8 ounces baby bella mushrooms, stems trimmed and caps halved
1 red onion, cut into 1/4-inch-thick rings
1 red bell pepper, cut into 1/4-inch-wide strips
1 zucchini, cut crosswise into 1/4-inch-thick slices
2 tablespoons vinegar
1/2 teaspoon salt
1/4 teaspoon ground black pepper
1/4 teaspoon dried oregano
5 cloves garlic, finely chopped