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best vegan onion tart with caramelized onions
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Caramelized Onion Tart

Homemade caramelized onion tart made with red onions, leek, and other healthy ingredients. This onion pie is called "Zwiebelkuchen" in Germany and it's a traditional fall recipe. The dish is vegan, gluten-free, soy-free, easy to make, flavorful, and delicious.
Course Main Course, Tart
Cuisine German
Prep Time 40 minutes
Cook Time 30 minutes
Total Time 1 hour 10 minutes
Servings 8

Equipment

  • Food processor*

Ingredients

Pie Crust:

  • 1 cup + 1 tbsp (160 g) gluten-free flour (*see notes)
  • 1/2 cup (60 g) almond flour (*see notes)
  • 2 tbsp (2 tbsp) ground flax seeds or chia seeds
  • 5 tbsp (5 tbsp) water
  • 2 1/2 tbsp (30 g) coconut oil softened
  • 1/3 tsp (1/3 tsp) sea salt

Onion Tart Filling:

  • 3 medium-large (300 g) onions peeled and diced
  • 2 medium (200 g) bell peppers diced
  • 2 small (130 g) stalks of leek finely chopped
  • 3 cloves (3 cloves) of garlic minced
  • 3 tbsp (30 g) chickpea flour
  • 1 heaped tbsp (10 g) cornstarch or arrowroot flour
  • 1/3 cup (80 ml) water or vegetable broth
  • 1 tsp (1 tsp) onion powder
  • 3/4 tsp (3/4 tsp) sea salt or more/less to taste
  • 1/2 tsp (1/2 tsp) paprika
  • 1/2 tsp (1/2 tsp) cumin (optional)
  • ground black pepper to taste
  • 1/2 tbsp (1/2 tbsp) fresh thyme or 1/2 tsp dry
  • 1 tbsp (1 tbsp) tamari or soy sauce (GF if needed) or coconut aminos
  • 3/4 cup (180 ml) plant-based milk
  • 7 oz (200 g) vegan cheese of choice (optional)
  • Fried onion rings on top (optional)

Instructions

  • Check the step-by-step process shots and the video above in the blog post.
  • Put 2 tbsp ground flax seeds (or ground chia seeds) to a small bowl, add 5 tablespoons of water and mix with a whisk. Set aside for 5 minutes.
  • For the pie crust, simply add all ingredients to a bowl and mix with a spatula or your hands until the dough sticks together. You can also use a food processor.
  • Press the dough into a greased/oiled 8-inch tart or pie dish and up the sides. Put it into the fridge.
  • Mix the chickpea flour, cornstarch, spices, and water or vegetable broth in a bowl with a whisk. Set aside.
  • Heat oil in a pan over low/medium heat and add the chopped onion, leek, and bell pepper. Cook the veggies with a lid on for about 15-20 minutes or until lightly caramelized, stirring frequently. Stir in garlic for the last few minutes and preheat the oven to 390 degrees Fahrenheit (ca. 200 °C).
  • Add the chickpea flour mixture and stir immediately, as it will thicken very quickly. Also, add plant-based milk and tamari.
  • Let simmer for a few more minutes (the mixture should thicken considerably), then turn off the heat. Pour the filling into the pie crust and smooth it evenly.
  • You can also add vegan cheese of choice (I used my easy vegan cheese sauce) and pan-fried onion rings on top but this step is optional.
  • Bake in the oven for about 25-30 minutes or until nicely browned. Enjoy! Store leftovers covered in the refrigerator for up to 3-4 days.

Notes

  • Gluten-free flour blend: I used 120 g (3/4 cup) rice flour and 40 g (5 tbsp) tapioca flour. A store-bought gluten-free flour blend (with similar ingredients) should work as well. You can also use regular flour or spelt flour if you're not gluten-free.
  • You can use finely ground nuts (e.g. hazelnuts, walnuts, cashews) or even ground sunflower seeds instead of almond flour (ground almonds).
  • Recipe serves 8. Nutrition facts are for one serving.
Nutrition Facts
Caramelized Onion Tart
Amount per Serving
Calories
216
% Daily Value*
Fat
 
9.1
g
14
%
Carbohydrates
 
26
g
9
%
Fiber
 
3.5
g
14
%
Sugar
 
4.1
g
5
%
Protein
 
4.9
g
10
%
* Percent Daily Values are based on a 2000 calorie diet.