Asparagus and caramelized onion tarts

I didn't make any token effort to stage this, since I snapped it quickly before whisking them away to an off-site dinner party.

Years ago, back in the ’90s, a group of friends got together periodically to cook a menu from Bon Appetit or Food and Wine or some such thing. It predated the supper club craze of the next decade by a bit, but it followed the same theory: Most of us (me excluded) wouldn’t make all of those lengthy menus on our own. There are still some definite keepers that came out of those gatherings (both recipes and people), and the people finally reassembled Saturday night for a revival of gourmet night. It was a total blast, with great food to boot, so we’ve already got promises of a next time on the horizon.

The menu was a bit more loosey goosey this time; more suggestion of ingredient or dish category than list. Our fabulous hosts (oh my heaven, I now have basement envy) made salmon with a dill sauce. I took the suggestion of asparagus and opted for this tart. The original recipe, which you can find here, called for mushrooms, but since at least one person among us doesn’t care for them, I decided caramelized onions would be a fine substitute in terms of offering the same substance and relative texture, while boosting the flavor quotient. I might like to try this some day with mushrooms, but it’s definitely a keeper with the caramelized onions.

Asparagus and caramelized onion tarts

Adapted from Betty Rosbottom via Bon Appetit, April 2009

Ingredients

2 large onions, caramelized (with 1 tsp. butter and oil if you’re doing the stove-top method)

1 package of frozen puff pastry (two sheets), thawed just until pliable (about 40 minutes in winter, less in summer)

2 tablespoons butter (or equivalent fat saved from caramelizing onions)

1 pound slender asparagus spears

¾ teaspoon kosher salt

¼ teaspoon black pepper

1½ teaspoons chopped fresh thyme, plus sprigs for garnish

1½ teaspoons lemon zest

½ cup crème fraiche

½ cup packed coarsely grated Gruyere

Method

Caramelize onions by your preferred method. Mine is the minimal fuss, foolproof, great-reward crockpot method I’ve blogged/raved about here, but you can use the stove top method: Cut onions into slices between 1/8 and ¼ inches (if you get them too thin they’re easy to burn). Heat 1 teaspoon olive oil and 1 teaspoon butter in the largest skillet you’ve got so they’ve got room to spread out and not just steam cook. Set the pan on medium low. Add onions, and cook, stirring periodically until they’ve given up and become deep golden brown but not burned. This can easily take 40 minutes and you need to pay attention. Hence the reason I rave about the wonders of the crockpot set-and-forget it method.

Once your pastry is thawed to just pliable, roll into a 10-inch square on a cutting board. (One side will probably already be 10 inches out of the box; you just need to roll it out the other side to make it square.) You shouldn’t need to flour the board if you haven’t overthawed the pastry. If it’s reached the sticky stage, refrigerate it a bit before rolling out so you don’t need to flour the board and toughen the pastry. Cut into 4 squares. Using a sharp knife, score a border one half-inch in from the edge of the squares, making sure not to cut all the way through the pastry. Place squares on two baking sheets. Chill until ready to use.

Melt 2 tablespoons butter. (Or if you’ve got any remaining fat from caramelizing the onions, you can use that to make up part of the amount.) Let cool slightly.

Snap off any tough ends of asparagus. Slice asparagus into 1½-inch pieces on the diagonal. Combine with butter, onions, salt, pepper, thyme leaves, lemon zest, crème fraiche and Gruyere.

Preheat oven to 400 degrees. Mound mixture on pastry squares, making sure to leave the ½-inch border uncovered. Place one sheet on a rack in the upper part of the oven and the other on a lower rack. Bake for 12 minutes, then flip positions of the baking sheets and cook for up to another 10 minutes. (Depending on your oven, it might be done a minute or so sooner, so watch them.) I baked mine for a total of 19 minutes between the two stages initially, then covered them with foil and transported them to the dinner party eight blocks away, where they were reheated while still foil covered in a 275-degree oven (my thanks to hostess Jodi). Garnish with thyme sprigs if desired.

Rating: Tasty. Those are all flavors I like separately, and combined the individual flavors still come through and combine nicely. It makes a nice presentation, so they’re a good dinner party first-course option. Ideally they wouldn’t have been transported and reheated, and would be best served shortly after their initial baking so they stay at their crispest, but they were remarkably forgiving of the abuse. This might look like a lengthy recipe, but they come together with minimal fuss or overall time commitment, with lots of make-ahead shortcuts. Overall, a great option for entertaining. Could make a meatless main dish for a lunch.

Make ahead tips: Onions can be caramelized a few days in advance. Just bring to room temperature before proceeding. Pastry can be rolled out, scored and placed on baking sheet, then covered and stored in the frig for up to a day. The asparagus filling can be mixed up a day in advance and kept in the refrigerator.