Mustard and Fennel Onion Galette

A Savory Symphony: Mustard & Fennel Onion Tart

Delight your taste buds with a flavorful adventure in baking! This delicious Onion Tart, enriched with the unique flavors of mustard and fennel, is perfect for gatherings or as a comforting home-cooked dish. Get ready to impress your guests or indulge in a slice all on your own!

Preparation Time

Approximately 2 to 2.5 hours, including rising time.

Ingredient List

• 1/4 teaspoons active dry yeast (one 1/4-ounce packet)
• 1/2 cup warm water (between 105 and 115°F)
• 1/2 to 3/4 cups all-purpose flour
• 1 large egg
• 1/3 cup plus 1 tablespoon extra-virgin olive oil, divided
• 1/2 teaspoons salt, divided
• 2 teaspoons fennel seeds
• 3 pounds yellow onions, halved and thinly sliced
• 1 tablespoon Dijon mustard (or a bit more, if preferred)
• 1/2 cup coarsely grated Parmigiano-Reggiano cheese

Key Considerations

Ensure that your yeast is active by verifying that the mixture foams within five minutes. While the onions take time to caramelize, the result is a sweet and savory depth that enhances the flavor profile of your tart. You can also prepare the dough and onions in advance to cut down on prep time when you’re ready to bake. Keeping your workspace clean and organized will also streamline the process.

The Cooking Process

Start by mixing your active dry yeast with the warm water in a small bowl, giving it about five minutes to become foamy. If it doesn’t foam, consider starting again with fresh yeast.

In a medium bowl, add 1/2 cups of flour and create a well in the center. Pour the yeast mixture into this well. In another bowl, combine the egg, 1 tablespoon of olive oil, and 1/2 teaspoons of salt, then add this blend to the yeast mixture. Gradually mix in the flour with a wooden spoon or your fingers until you form a soft dough. Transfer the dough to a floured surface and knead it gently, adding up to 1/4 cup more flour as needed, until smooth and elastic (approximately 5 minutes). Place the dough in an oiled bowl, coating it with oil, then cover it with plastic wrap and let it rise in a warm place until it doubles in size (about 1 to 1.5 hours).

While the dough is rising, heat the remaining 1/3 cup of olive oil in a large skillet over medium-high heat. Once it shimmers, add the fennel seeds and sauté them until they darken slightly (around 30 seconds). Next, introduce the sliced onions along with the remaining salt and half a teaspoon of pepper. Lower the heat to medium-low and cover the onions with a parchment paper round. Cook them, stirring occasionally, until they are tender and golden brown (about 1 to 1.25 hours).

[Tip: You can prepare the dough and onions a few hours in advance. Refrigerating the dough and keeping the onions at room temperature until you’re ready to assemble the tart can save time.]

When ready to bake, preheat your oven to 375°F, positioning the rack in the middle.

Gently knead the dough on a floured surface to deflate it. Shape the dough into a 15 by 12-inch rectangle on a heavy baking sheet, ensuring to fold or crimp the edges to create a crust. Spread a layer of mustard over the dough, leaving a half-inch border. Evenly distribute the sautéed onions on top of the mustard, followed by a generous sprinkle of Parmigiano-Reggiano cheese.

Bake the tart for 30 to 35 minutes or until the crust is golden brown. Cut into squares or diamonds, and serve warm or at room temperature for a delightful culinary experience!