Caramelized Onion and Mushroom Tart
Slow-cooked caramelized onions and cremini mushrooms fill a flaky, dairy-free pastry crust in this savory tart seasoned with fresh thyme. The long caramelization — about 40 minutes on its own — is what gives the filling its deep, sweet-savory flavor. Serve it for brunch, as a starter, or as a light main course.
Equipment
- 10-inch tart pan with removable bottom
- Skillet or sauté pan
- Mixing bowl
- Rolling Pin
- Oven
- Parchment paper
- Pastry brush
Ingredients
For the Tart Crust:
- 1 ¼ cups all-purpose flour preferably unbleached
- ¼ tsp sea salt
- ½ cup vegan butter chilled and cut into small cubes
- 3 tbsp ice water more as needed
For the Filling:
- 2 tbsp olive oil extra virgin
- 2 large yellow onions thinly sliced
- 1 tsp organic cane sugar to help caramelize the onions
- ½ tsp balsamic vinegar
- 3 cups cremini mushrooms sliced
- 3 cloves garlic minced
- 1 tsp fresh thyme leaves or 1/2 tsp dried thyme
- ½ tsp sea salt to taste
- ¼ tsp black pepper freshly cracked
- ½ cup unsweetened vegan cream or cashew cream
Instructions
Make the Tart Crust:
- In a large bowl, whisk together flour and salt. Using your fingertips or a pastry cutter, work the chilled vegan butter into the flour until the texture resembles coarse crumbs with pea-sized bits.
- Add ice water, 1 tablespoon at a time, mixing gently until the dough just holds together. Form into a disc, wrap in parchment paper, and chill in the fridge for 30 minutes.
- Preheat oven to 375°F (190°C). On a floured surface, roll out the chilled dough into a 12-inch circle. Gently press into a 10-inch tart pan. Trim the edges, prick the base with a fork, and pre-bake for 10 minutes.
Prepare the Filling:
- Heat olive oil in a skillet over medium heat. Add sliced onions and sugar and sauté, stirring occasionally, for 25–30 minutes until deeply golden and caramelized. Stir in balsamic vinegar and cook 1 more minute.
- Push onions to the side and add mushrooms to the pan. Cook 8–10 minutes until browned, then stir in garlic and thyme and cook for another 2–3 minutes. Season with sea salt and pepper. Remove from heat.
- Spoon the caramelized onion and mushroom mixture into the pre-baked tart shell. Pour in vegan cream, allowing it to settle between the onion and mushrooms without overflowing.
- Bake at 375°F (190°C) for 20–25 minutes until the filling is set and lightly golden on top. Let cool for 10 minutes before slicing.
Notes
- For a gluten-free version, use a gluten-free flour blend with xanthan gum for the pastry crust.
- For deeper flavor, deglaze mushrooms with a splash of dry white wine before adding garlic and thyme.
- Cashew cream offers a richer, neutral flavor in the filling compared to store-bought vegan creams.
Nutrition
Calories: 334kcalCarbohydrates: 29gProtein: 6gFat: 23gSaturated Fat: 6gPolyunsaturated Fat: 4gMonounsaturated Fat: 8gTrans Fat: 0.1gSodium: 491mgPotassium: 277mgFiber: 3gSugar: 4gVitamin A: 737IUVitamin C: 5mgCalcium: 39mgIron: 2mg
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