1. Heat oven to 400 degrees. Toss together potatoes, 2 tablespoons oil, capers, 3/4 teaspoon thyme, 1/2 teaspoon rosemary, and 1/2 teaspoon salt in a bowl until evenly coated.
2. Heat 2 tablespoons oil in a large skillet over medium heat until shimmering. Add onions, sugar, and 1/2 teaspoon salt and cook, stirring often, until onions are golden brown, about 20 minutes. Add garlic and remaining thyme and rosemary and cook for 1 minute. Whisk in vermouth, scraping up any brown bits, and cook until liquid has evaporated, 1 to 2 minutes. Remove from heat and season with salt and pepper to taste.
3. Arrange 1/3 of the potato mixture evenly in the bottom of a greased 9x13" baking dish. Sprinkle roasted red peppers over potatoes and top with another 1/3 of the potato mixture. Spread onion mixture evenly over potatoes and top with the remaining potato mixture and any accumulated liquid; reserve bowl.
4. Toss zucchini with 1 tablespoon oil and 1/2 teaspoon salt in reserved bowl and shingle over potatoes. Cover tightly with aluminum foil and bake for 1 hour.
5. Meanwhile, toss Parmesan, panko, lemon zest, and remaining 3 tablespoons oil together in a bowl. Remove foil, sprinkle panko mixture evenly over gratin, and continue to bake until golden brown, 25 to 30 minutes. Let cool 15 minutes. Sprinkle with parsley and serve with lemons.
Source: Hannaford fresh Magazine, March - April 2016