Feel free to substitute any other vegetables for those listed. 

Ingredients:

2½c. unbleached all-purpose flour (360 g)

2sticks (½ pound) unsalted butter, cut into pieces and kept cold

2tsp. fine sea salt

¾c. ice water

2 tsp. freshly squeezed lemon juice

Rough Puff Pastry:

Tart Filling:

1large sweet onion, peeled and thinly sliced

2 tbsp. olive oil

½ tsp. coarse kosher salt

Pinch of black pepper

1/8 tsp. granulated sugar

2/3 c. shredded or grated Parmesan, Asiago or fontina cheese 

1 large green zucchini, ends trimmed and zucchini cut lengthwise into thin slices

1 large yellow zucchini, ends trimmed and zucchini cut lengthwise into thin slices

2 sweet peppers, seeded and cut into ½-inch strips

2-3 garlic cloves, finely minced

2-3 tbsp. olive oil

1 tsp. coarse kosher salt

¼ c. grated Parmesan cheese

¼ tsp. freshly ground black pepper, plus more for garnishing

¼c. fresh basil leaves (or any other fresh herb), cut or torn into small pieces, plus more for garnishing

Directions 

Rough Puff Pastry:

Place flour and butter into bowl of standing mixer fitted with paddle. Mix on low speed for 30 seconds or until butter is broken up in large chunks and is still visible.

Add salt to water in a small bowl and stir until dissolved. Stir in lemon juice. With machine on low speed add to flour mixture. Mix until dough just comes together in a rough ball. Remove dough from mixer and place on a lightly floured counter. (Dough should still be shaggy and moist. It will become smooth and hold together after rolling and folding as described below.)

Using your hands, flatten dough into a 6-inch square and enclose with plastic wrap. Set dough package in refrigerator for at least 20 minutes and up to an hour.

Unwrap dough and place it onto a lightly floured countertop. Roll dough out into a rectangle, 18 inches by 6 inches, with one long side facing you. Beginning on right side, fold a third of the dough over the center of the rectangle, then fold the remaining left third of the dough over it, like an envelope.  

Repeat the rolling and folding technique once more and then wrap dough square in plastic or aluminum foil and refrigerate for at least 20 minutes and up to an hour.

Unwrap dough and place onto a lightly floured countertop. Roll dough into the same size rectangle as indicated above, brushing excess flour from each third of the folded dough. Rewrap dough and refrigerate for at least 20 minutes and up to an hour.

Unwrap dough and place onto a lightly floured countertop, open seam-side facing you. Roll and fold the dough one last time. Wrap and refrigerate for at least an hour and up to one week. Dough can also be wrapped well in a freezer bag and kept frozen for up to a month. To thaw pastry, place in refrigerator overnight.

On a lightly floured counter, roll out pastry a quarter-inch thick to fit into a 9-by-13-inch baking pan. (You will probably have extra pastry. Follow directions for freezing it for later use.)

Prick pastry all over with a fork and set into freezer for at least 10 minutes. (It can also be frozen at this point, if well wrapped, for up to one month.)

Heat oven to 425 degrees. 

Randomly prick pastry with a fork and cover it with a sheet of parchment paper or aluminum foil, leaving the edges or crust uncovered. Fill lined pastry with pie weights or dried beans. Bake for 10 minutes.

Transfer pan to a cooling rack and carefully lift up parchment paper along with weights or beans. Place pan with pastry back into oven and bake until light golden brown, an additional seven to eight minutes. Let cool.

Filling

Heat oil in a large skillet over medium heat. Add onions and sauté until translucent, about 10 minutes. Add salt, pepper and sugar; stir and continue to sauté onions until they begin to caramelize, about 15 minutes more. Transfer onions to a plate to cool; reserve.

Heat oven to 425 degrees. Line a large baking pan with parchment paper or lightly oil it.

Toss all cut-up vegetables and garlic in a large bowl with olive oil, salt and fresh basil. Spread vegetables onto prepared pan and bake for 15 minutes. Set pan onto a cooling rack; let vegetables cool.

Reduce oven temperature to 375 degrees and sprinkle cooled prebaked pastry with Parmesan cheese. Arrange onions over cheese and scatter roasted vegetables over it, cutting vegetables if necessary to fit. Sprinkle vegetables lightly with Parmesan cheese.

Brush edges of tart with an egg whisked with a teaspoon of water, if desired, and bake tart for eight to 10 minutes or until pastry is golden brown.

Before serving, grind some black pepper over the top and garnish with minced fresh herbs.

Makes 6-10 servings.