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best vegan onion tart with caramelized onions

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


  • Food processor*


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 of (3 cloves) 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)


  • 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.


  • 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
% Daily Value*
* Percent Daily Values are based on a 2000 calorie diet.