Zucchini and Onion Gratin

By joanmarie

Ingredients

• 2 tablespoons olive oil, divided $
• 1 large onion, quartered lengthwise and thinly sliced
• 1 tablespoon tomato paste $
• 2 teaspoons grated lemon rind $
• 1 teaspoon fresh thyme leaves
• 3/8 teaspoon kosher salt, divided
• 1/4 teaspoon freshly ground black pepper $
• 1 1/2 pounds zucchini, diagonally sliced into 1/4-inch-thick pieces
• 1 ounce Parmesan cheese, grated (about 1/4 cup) $

Details

Preparation time 21mins
Cooking time 45mins
Adapted from cooing light.com

Preparation

Step 1

1. Heat a large skillet over medium heat. Add 1 tablespoon oil to pan; swirl to coat. Add onion; cook 6 minutes, stirring occasionally. Stir in tomato paste; cook 2 minutes. Stir in rind, thyme, 1/8 teaspoon salt, and pepper; cook 2 minutes, stirring occasionally.

2. Preheat broiler to high.

3. Arrange zucchini on a jelly-roll pan. Drizzle with remaining 1 tablespoon oil; toss. Broil 7 minutes or until lightly charred. Sprinkle with remaining 1/4 teaspoon salt.

4. Preheat oven to 375°.

5. Spread onion mixture in a 2-quart gratin dish. Arrange zucchini mixture over onion mixture. Sprinkle with cheese. Cover and bake at 375° for 25 minutes. Remove from oven.

6. Preheat broiler to high.

7. Uncover zucchini mixture; broil 1 1/2 minutes or until lightly browned.