Savory Asparagus Tart with Mustard, Caramelized Onions, Lemon, and Tomme

This asparagus tart is a springy riff on the potato tart that I made at the farm late last summer. Then, I was working with a wheel of goat tomme that Arlene had made, but this time I was lucky enough to use a hunk of the cow tomme that I made in the fall with my very own shaky, inexperienced hands. After letting four wheels age a full five months in the cave, we finally cut one open late last week, and it tasted dang delicious. I was shocked. The black stripe of vegetable ash—made famous by Humboldt Fog—isn’t traditional to tomme-style cheeses, but it gave this wheel some beautiful character and a deep, delicious saltiness that made it a lovely candidate for baking.

Even so, don’t let the specialty cheese sway you from baking your own version of this tart. Any sort of semisoft or hard cheese would do, from gruyère to sharp cheddar, or even ricotta salata. And although this recipe uses a cow’s cheese, a hard goat’s or sheep’s cheese would be so at home with the asparagus and caramelized onion. On a more personal note, I also really enjoyed making this because it reflects two very important seasons in my life: the momentum of spring now and ahead, and my formative fall at the farm. Special to make, special to eat—it really had no choice but to be good.

Olive Oil Press-In Crust

I like to use this olive oil crust when I’m baking for my butter-wary parents. Feel free to substitute your favorite buttery pastry dough, such as this one.

1 1/2 cups all-purpose or pastry flour

Heaping 1/2 teaspoon flaky sea salt

1/4 teaspoon baking powder

1/3 cup olive oil

3 to 5 tablespoons cold milk or water

1. Combine all the dry ingredients in a medium bowl. Pour olive oil and first three tablespoons of milk in, and whisk with a fork until mixture is evenly blended and somewhat moist. If need be, add an extra tablespoon or two of milk to get moist, crumbly consistency.

2.  Press dough crumbles into an 8- or 9-inch tart pan, using a metal measuring cup to ensure even edges that are flat against the bottom and sides. Pop into the fridge while you prepare the filling.

Savory Asparagus Tart

Makes one 8- or 9-inch tart

1 pound asparagus, from about one bunch

1 large yellow onion, sliced into thin rings of half-moons

1 tablespoon Dijon mustard

¾ cup heavy cream or half-and-half

1 large egg

Zest of half a lemon

½ teaspoon flaky sea salt

1/3 cup grated hard cheese such as asiago, gruyere, or tomme (I used farm-made cow tomme!)

Olive oil

Pinch red pepper flakes

Cracked black pepper

1.  Preheat oven to 350 degrees F.

2.  Caramelize onions: heat a medium, heavy-bottomed saucepan for two to three minutes over medium heat until it’s quite warm. Turn heat all the way low, and add onions to the dry saucepan. Stir for about two minutes, then cover, and leave to cook for 15 to 20 minutes, checking occasionally and stirring onions as needed. By this point, they should smell sweet and be browning evenly. Add a tablespoon or so of olive oil and a pinch of salt, and, stirring every few minutes, continue to cook uncovered for another 15 to 20 minutes until the onions are very dark brown. Remove from heat and set aside.

3.  Cook asparagus: fill a medium saucepan with water and bring to boil. Snap off all of your woody asparagus ends, and boil the spears for just one minute. Drain immediately and run under very cold water to stop the cooking. Pat asparagus dry. Heat two tablespoons of olive oil in a medium saucepan and when it’s hot, add asparagus. Top with a few pinches of red pepper flakes and a small pinch of salt, and allow asparagus to brown for about five minutes. Flip, and cook the other side for another five minutes. Remove from heat and set aside.

4.  Assemble and bake:  whisk the egg, cream, zest, and salt in a small bowl and set aside. Retrieve your tart crust from the fridge, and spread the mustard across the bottom (an offset spatula makes this easy). Arrange onions in an even layer across the bottom, then top with asparagus spears. I lined mine up tightly and side to side like soldiers across the whole tart, alternating tops and bottoms, then tucked the remaining spears into the bare shoulders of the pan. Pour cream mixture over the top of tart, then top evenly with cheese. Crack some black pepper over the top, slide onto a cookie sheet, and bake for 45 minutes until tart is evenly browned. Allow tart to cool for 15 minutes before removing from pan. Cut slices with a very sharp knife—leftovers will keep for about three days.

Gérard's Mustard Tart with Olive Oil Crust

Ever since my sister and I nearly killed our dad with butter five years ago, I try to lay off the baked goods around my folks. Turns out that creamy Brussels sprouts, cake, pie, and steak do not a healthy ticker make, so we do our best to leave the bad (aherm, good) shit at home when hanging with mom and dad. We need to work on roughage ‘round these parts, and if that means slapping some vegetables into a barely eggy, cheeseless tart, then so be it.
 
Dorie Greenspan, of whom I didn’t realize a full-fledged admiration until recently, shared this tart over on Bon Appétit and in Around My French Table a few years ago. She winds a fancy-free yarn about its French provenance and mentions that it’s an autumn take on a summer tart made with tomatoes (definitely making that one come July). Fancy-free, but not butter-free, so we made this with a dad-safe olive oil press-in crust instead; it’s probably not actually healthier, but it felt mighty fine to eat. In the end, the whole she-bang tasted, for some reason, like chicken noodle soup, and in this blustery San Diego weather (har har), that makes it just the roughage ticket.

 
Gérard's Mustard Tart
Adapted from Dorie Greenspan, by way of Bon Appétempt

This easy olive oil press-in crust ended up tasting like a delicious cracker, which suited this tart just great. Add some chopped herbs or cracked pepper if you're looking for an extra kick! Another added benefit of this crust is that it cuts the make time down by a couple hours: just mix the dough and go. As for the filling, I really liked it, but would have loved it had I caramelized or browned the veggies over the stove instead of steaming. I've included browning instructions below for those who suspect they'd prefer it that way too.

For olive oil press-in crust
1 1/2 cups all-purpose or pastry flour
Heaping 1/2 teaspoon flaky sea salt
1/4 teaspoon baking powder
1/3 cup olive oil
3 to 4 tablespoons cold milk or water

1. Combine all the dry ingredients in a medium bowl. Pour olive oil and first three tablespoons of milk in, and whisk with a fork until mixture is evenly blended and somewhat moist. If need be, add an extra tablespoon or two of milk to get moist, crumbly consistency.

2.  Press dough crumbles into a 9-inch tart pan, using a metal measuring cup to ensure even edges that are flat against the bottom and sides. Pop into the fridge while you prepare the filling.

For filling
3 thin carrots, trimmed and peeled
3 thin leeks, white and light green parts only, cut lengthwise in half and washed
2 rosemary or thyme sprigs
3 large eggs
6 tablespoons crème fraîche or heavy cream (I used light sour cream)
2 tablespoons Dijon mustard, or to taste
2 tablespoons grainy mustard, preferably French, or to taste
1/8 teaspoon cayenne pepper, optional
Sea salt and white pepper, to taste
Freshly ground black pepper

1.  Center a rack in the oven and preheat the oven to 425 degrees F. Line a baking sheet with a silicone baking mat or parchment paper.

2.  Cut the carrots and leeks into slender bâtons or sticks: First cut the carrots lengthwise in half, then place the halves cut side down on the cutting board and cut crosswise in half or cut into chunks about three inches long. Cut the pieces into 1/ 8- to 1/4-inch-thick matchsticks. Cut the leeks in the same way. (Make sure that they’re really only about three inches long, otherwise the veggies are difficult to spoke.)

3.  Fit a steamer basket into a saucepan. Pour in enough water to come almost up to the steamer, cover, and bring to a boil. Drop the carrots, leeks, and one rosemary or thyme sprig into the basket, cover, and steam until the vegetables are tender enough to be pierced easily with the tip of a knife, 10 to 15 minutes. Drain the vegetables and pat them dry; discard the rosemary sprig.

Alternately: Saute the carrots and leeks over medium-high heat in a large pan coated with olive oil. If you go this route, do your best to keep the leek layers together; cook the vegetables until they start to brown, about 12 minutes; and add the chopped herb sprig to the filling instead of the steamer basket. I’ll cook it this way next time.

4.  In a medium bowl, whisk the eggs together with the crème fraîche or heavy cream. Add the mustards, season with salt and white pepper, and cayenne if you’re using—mustard has a tendency to be salty, so proceed accordingly—and whisk to blend. Taste and see if you want to add a little more of one or the other mustards.

5.  Put the tart pan on the lined baking sheet and pour the filling into the unbaked crust. Arrange the vegetables in and over the filling, pushing them down into the filling as needed; I used all my carrots but had extra leeks, even though I really crammed ‘em in there. Top with the remaining rosemary or thyme sprig, and give the vegetables a sprinkling of salt and a couple cracks of black pepper.

6.  Bake the tart for about 30 minutes, or until it is uniformly puffed and lightly browned here and there, and a knife inserted into the center of the custard comes out clean. I ran mine under the broiler for about 30 seconds at the end, just to give it a bit deeper of a browning. Transfer the tart to a cooling rack and let it rest for five minutes before removing the sides of the pan. Serve hot, warm, or at room temperature. Will keep for three to four days, covered in the fridge.