Warm Red-and-Yellow-Tomato Tart With Goat-Cheese Sauce

Serves six.

3 large Spanish onions, sliced very thin
Salt and freshly ground white pepper
2 tablespoons butter
Pinch of sugar
1 pound puff pastry (if frozen is used, 2 sheets, partially defrosted)
3 large yellow and 3 large red beefsteak tomatoes
2 tablespoons olive oil
3 tablespoons basil chiffonade

Goat-cheese sauce:
8 ounces fresh goat cheese
1 cup milk
2 cloves garlic, crushed
1 sprig rosemary
Salt and cayenne

Basil oil:
3 cups packed basil leaves
3/4 cup grape-seed oil
1 teaspoon salt

Cooking Instructions
Preheat the oven to 425 degrees. Toss the sliced onions with salt and pepper. Melt the butter in a large sauté pan over medium heat. Add the onions and cook, covered, for about 15 minutes. Remove the lid and add a pinch of sugar. Increase the heat and cook until the onions are nicely caramelized, stirring occasionally, about 10 minutes. Remove onions from pan, and set aside on a plate to cool.

Place puff pastry on a cutting board and, using a 4-inch ring, cut out 6 disks. Prick pastry with a fork and place on a baking tray lined with parchment. Place another sheet of parchment on pastry and an additional baking tray on top to keep pastry from rising too high. Bake until pastry turns golden brown, about 15 to 20 minutes. Remove top tray and parchment and allow tart shells to cool.

Blanch tomatoes in 4 quarts of boiling water for 15 seconds each, and immediately move them to a large bowl of ice water. Peel, seed, and remove the interior ribs from each tomato. Cut tomatoes into 1/4-inch dice.

Goat-cheese sauce:
Crumble goat cheese into mixing bowl. Place milk, garlic, and rosemary in a medium saucepan, and bring to a boil. Remove from heat and allow to sit, covered, for 15 minutes. Reboil mixture and strain milk onto crumbled cheese, whisking until completely smooth. Use additional milk or hot water to thin sauce if desired. Season with salt and cayenne.

Basil oil:
Bring 2 quarts of water to a boil. Use about 1/4 cup salt per quart of hot water. Drop basil into boiling water for 15 to 20 seconds, and immediately plunge basil into ice water to chill. Drain, and squeeze out as much water as possible. Cut basil into small pieces and place in a blender with oil and salt. Blend on high speed for 2 minutes. Allow to sit for 10 minutes. Strain purée through a sieve lined with cheesecloth . Discard the cheesecloth, and reserve purée that remains (it can be added to mayonnaise, pasta, or mashed potatoes).

Spread the caramelized onions on top of pastry shells. Mix the red and yellow diced tomatoes together in a bowl, and mound on top of the onions. Season with salt and pepper, then drizzle with olive oil. Bake tarts for 5 minutes or until they are warmed through. Place on six serving plates and garnish with basil chiffonade. Drizzle warm goat-cheese sauce and basil oil around tarts and serve.