I know it's not autumn anymore but this recipe was too good not to share. Tarts were the first baking endeavor I really felt confident in, and as a result I will put just about anything–sweet, savory, or better yet a mix of both–in a tart pan. Is anything made worse by adding a crust?
This recipe was inspired by Bon Appetit and made better by quarantine-induced modifications. Limitations do spark creativity, do they not? I had no butternut squash on hand and I don't know what a delicata squash is, much less whether I can find it in France, so I used sweet potato, red onion, and potimarron, which google tells me is called Red Kuri Squash in English. You can use a mixture of whatever squashes and gourds grow best in your region–I really don't think there's a way for the result not to taste good. I also added some crème fraîche (the French have trained me well) to the caramelized onion mixture, which provided much-needed moisture in the base, and I left out the mustard because mustard is, well, disgusting (I guess the French have not trained me that well after all).
The biggest substitution-turned-revelation was the pastry crust. As France headed into lockdown, flour started disappearing from the supermarket shelves. As you may know from previous posts, Laur is a very diligent shopper, and her many attempts to buy us flour while not fully understanding the French packaging (bless her heart) resulted in two bags of flour that I had never bought before: farine de blé noir (alias buckwheat) and farine fluide (T45 pastry flour). I combined these with butter in a 1:1:1 ratio and the result provided a gorgeous earthiness that really grounded the richness of the tart. The Bon Appetit recipe calls for a whole wheat crust which I imagine would have a similar effect, but the buckwheat really brought something special in my opinion. Buckwheat is also gluten-free, so I imagine that combining it with gluten-free pastry flour would be a good alternative for those with gluten sensitivities. But a word of caution: I have since tried making this dough with buckwheat and all-purpose flour, and it was a crumbly mess. I am normally the substitution queen, but the pastry flour makes a real difference in binding the dough. If you're really in a pinch and have to use a less fine flour, you might want to add a couple tablespoons of cornstarch or xanthan gum. If you try this please let us know in the comments how it works!
This recipe certainly requires time, but it is not actually that difficult in terms of skill level. I have always steered clear of recipes like this that rely on slicing things very thin because I don't have a mandoline and my knife skills subpar, but squash is pretty flexible and slicing with my chef's knife was perfectly fine. I have also been scared of these pinterest-worthy rose pattern tarts ever since I tried and failed to do it with apples, but squash is much more pliable and forgiving than apples are. Don't be afraid!
A very wise friend once told me not to let good wine gather dust waiting for a special occasion; opening a good bottle of wine turns an ordinary evening into a special one. This was revolutionary advice for my romantic side (I can just hear all my exes saying "What romantic side?"), but I think it also applies here. This tart is an absolute showstopper as a vegetarian Thanksgiving centerpiece, but you shouldn't wait until then to serve it. Take it from an impatient person: the best things come to those who don't wait!
Ingredients
For the pastry:
100 g buckwheat flour
100 g pastry flour
100 g butter - cold, unsalted, cut into small cubes
1 tsp salt (or leave out salt if butter is salted)
For the filling:
1 small sweet potato
1/2 potimarron/Red Kuri squash or your gourd of choice
1 red onion
3-4 yellow onions
100 g/4 oz coarsely grated Gruyère cheese
20 cl crème fraîche (or sour cream)
30 g/2 tbsp unsalted butter
A few sprigs of fresh thyme (though dried will work too)
Pinch of cayenne pepper (or piment d'espelette for my friends in France)
Olive oil
Salt - ideally both fine kosher and flaky sea salt
Steps
Caramelize the onions: Start this step first since caramelized onions are a waiting game. Halve the yellow onions and slice thinly lengthwise. Heat 2 tbsp of olive oil in a large saucepan over medium-low heat and add onions. If the onions fill more than 1/3 of the volume of your pot, add them in batches as each round softens so that you can stir easily. Check them often while following the next steps and keep them on fairly low heat - they can burn quickly if you forget to stir. If they start to stick to the pan, add a little water and scrape the bottom to mix in the good sticky bits. It will take about 40 minutes for them to reach a deep golden brown, so probably right around when you are rolling out the crust.
Make the crust: Once the onions are cooking, start on the crust. Mix dry ingredients and then add in small cubes of cold butter. If you have a food processor, you can throw everything in there and blitz until you get small breadcrumb-like pieces. Add cold water a tablespoon at a time until the dough comes together. If you don't have food processor, work the butter into the flour with your fingertips until you achieve the same breadcrumb-like consistency, and work in a small bit of cold water until it comes together in a moldable dough. Form the dough into a ball. If the dough resists molding or feels crumbly still, add a bit more water; otherwise it will fall apart when you roll it out. Wrap in plastic and refrigerate for 30 minutes. Note: You do NOT need to knead pastry dough for tarts. Keeping it chilled is essential to the texture and overworking it will warm it too much. If it's starting to get warm (especially if you are making dough by hand), run your hands under cold water or stop and put everything in the refrigerator for a few minutes.
Preheat the oven to 170º C/350º F. (I bake on 150º C because my oven is aggressive - adjust as necessary.)
Prepare the filling: While the dough is chilling, start slicing your vegetables, keeping them all in separate piles. Chop the red onion in half and slice lengthwise as thinly as possible, taking care to keep the layers of the half-rounds intact (as opposed to falling apart into strips). Peel the sweet potato and cut in half lengthwise, then thinly slice into half-moons as well. Peel the squash and thinly slice lengthwise into long arcs. Keep an eye on your onions and jump to step 5 if they are looking browned.
Once dough has chilled for thirty minutes, roll out into a large circle, about 3 mm or 1/8 inch thick. Gently lay over a fluted tart pan with a removable bottom and press into the mold evenly, cutting off any overflow but leaving a little bit of excess as crust tends to shrink while baking. Using a fork, poke holes all over the base. Place crust in freezer until ready to bake.
At this point your onions should be well caramelized. Add kosher salt to taste and a small splash of water when they are reaching the end to rehydrate and unstick them, and remove them from heat when the water is absorbed. Stir in the leaves from 1 sprig of thyme and cool.
Once the onions have cooled, stir in a couple big dollops of crème fraîche. You can add the full amount or stop once you have reached a nice creamy consistency and the cream is holding the onions together. You don't want more cream than onions.
Assemble: Take your crust back out of the freezer. Sprinkle a pinch of cayenne pepper over the base, and then spread the caramelized onion mixture over it. Now here's the fun part: layer the vegetables and red onion in concentric circles from the outside in. I did squash, sweet potato, red onion, squash, sweet potato, red onion because I wanted all the flavors in each bite, but follow your heart. Once you get to the center, roll your most pliable small slices and layer one inside the other to make the center of the rose. If you have leftover vegetables, add them into any spaces that look thin; the vegetables will soften as they roast so don't be afraid to really layer them.
Brush with olive oil and sprinkle on a pinch flaky sea salt. Bake until the crust is golden and the vegetables are browned and crisped (the edges may even char, which is fine), about 45-50 minutes in my wonky oven but probably closer to 60-75 minutes in a normal oven.
Almost there! In the meantime, melt the butter in a small saucepan with the remaining thyme (full sprigs) until fragrant and just bubbling. Once the tart is baked, brush butter all over and serve.
Comments