I was at a party a few evenings ago and was asked a question by someone who had clearly had too much to drink: If I was stuck on the planet Mercury and could only bring three items (these items must be edible) what would I bring? Hmm. Since Mercury gets plenty of sun and since my pale skin loathes the sun, I would bring a large hat fashioned from a tasty sourdough boule. I would also bring a rocket ship made out of some sort of heat resistant lunchmeat circa 1976 (hold the Velveeta) to set me free. And I would totally bring this caramelized onion and mushroom tart along for the long journey home.
This tart is my go to recipe whenever I have people over, and it usually vanishes before I have time to grab a piece. It’s extremely versatile – serve it warm, serve it at room temperature. Serve it at brunch, as an appetizer or paired with a green salad for a simple dinner.
If you’re a vegetarian, just omit the bacon, it’ll still be great.
The recipe for the dough will yield enough two 9 inch tarts or pies. I usually freeze the extra, in case I have the urge to bake something in the middle of the night, but you can certainly cut this recipe in half.
- Tart Dough:
- 2 1/2 cups all purpose flour
- 1 tbs sugar
- 1 tsp kosher salt
- 1 cup (2 sticks) unsalted butter - cold, diced
- 6 tbs ice water
- Onion & Mushroom filling:
- (Adapted from Martha Stewart)
- 4 tbs unsalted butter
- 2 cups sweet yellow onions, sliced thin
- 2 1/2 cups sliced mushrooms such as cremini, shiitake or oyster
- 2 cloves garlic
- 1/4 cup slab bacon, diced
- 1 tbs dijon mustard
- Fresh thyme and Italian parsley, chopped
- Salt and pepper to taste
- 1 cup smoked gouda and sharp cheddar cheeses, shredded
- Drizzle of white truffle oil
- 1 large egg, beaten, for egg wash
- Preheat oven to 400°
- In the bowl of a food processor combine flour, sugar, salt and butter. Process until dough looks like coarse meal, then add ice water, one tablespoon at a time until soft pliable dough forms.
- Gather dough into ball and cut in half. Flatten into disks, wrap in plastic and refrigerate one hour.
- Meanwhile, make filling:
- In large skillet heat 2 tbs butter until melted. Add onions and cook over medium low heat, until light brown and caramelized. Remove onions from pan and add bacon. Cook until partially crisp, then add mushrooms, adding more butter if needed. Continue to cook until mushrooms are softened. Add mustard, caramelized onions, herbs, salt and pepper, then set aside to cool slightly.
- Place one disk of dough onto floured surface and roll out into a 10 x 16 inch rectangle, about an 1/8" thick. Transfer to a parchment lined sheet pan and add filling. Spread mushroom-bacon mixture over dough, leaving a 2 1/2-inch border. Sprinkle with cheeses, and drizzle with truffle oil. Fold in edges and brush crust with egg wash. Bake until golden brown and center is bubbling, about 35 minutes.