Tarts are one of my favorite things to bake…and eat. With the perfect balance of buttery crust and filling, they are a meal on their own. They also make a great side dish or a knockout accompaniment to soup and salad. This red onion and coriander version has a warm flavor and light quality that I enjoy with a roast. It’s delicious all by itself too.
When cooked low and slow, red onions become even more sweet. Instead of pairing them with more savory spices, I decided to celebrate all that sweetness in this version. Ground coriander and a small amount of very fine orange zest play well with caramelized red onions.
¾ cup all purpose flour
½ cup whole wheat flour
1 teaspoon brown sugar
¼ teaspoon salt
6 tablespoons butter
4 tablespoons iced water
3 tablespoons olive oil
3 medium red onions, sliced
2 teaspoons balsamic vinegar
2 teaspoons brown sugar
½ teaspoon ground coriander
⅛ teaspoon microplaned orange zest
½ cup of half and half
Salt and pepper
Prepare the pastry dough by pulsing the all purpose flour, whole wheat flour, salt, brown sugar, and salt a few times in a food processor to combine. Cube the butter, add it to the flour mixture, and pulse until the mixture resembles breadcrumbs. Add the iced water one tablespoon at a time, using just enough so that the dough holds together but remains crumbly when pressed. Turn the dough onto your work surface, knead minimally, and shape into a flattened disk. After wrapping the disk in plastic, refrigerate for one hour.
Once the dough has chilled, roll it out to line a 14” x 4 ¼” rectangular tart pan. Cover and refrigerate the lined tart pan while you prepare the filling.
When caramelizing onions, the key is to cook them moderately low and slow, as their natural sugars take a while to brown and develop a richer sweetness. Heat the olive oil in a large skillet over medium-low heat, and add the onions – being careful not to overcrowd them. Stir often but not constantly, as the onions need to remain in contact with the hot surface to caramelize. If you find that the onions are cooking too quickly, adjust the heat accordingly. The entire process should take about 45 minutes to an hour.
Once the onions have caramelized, add the balsamic vinegar to deglaze the pan and release any browned bits. Remove the pan from the heat and stir in the brown sugar, ground coriander, and orange zest. Season the onion mixture with salt and pepper to taste.
Preheat the oven to 350 degrees. Line the tart with aluminum foil and fill with beans or pie weights. Blind bake for 10 minutes. Remove the foil and weights, and bake for 5 more minutes. Remove the crust from the oven and raise the temperature to 400 degrees.
Spread the red onions evenly on the base of the crust. Whisk the half and half and egg. Add ½ teaspoon salt and a generous amount of freshly cracked black pepper. Pour this mixture over the red onions. Bake for 25 minutes and serve warm.