Caramelized Onion Tart
This caramelized onion tart is a super-simple recipe using only six ingredients and very basic kitchen equipment. But I promise you, every person who tries this tart will ask you for a recipe.
One thing I learned from my years of being a vegan content creator is that I don’t always have to reinvent the wheel. The best recipes are often simple, affordable, and a take on a classic.
This caramelized onion tart pairs red onions with sweet maple syrup and balsamic vinegar, creating a timeless flavor profile. Baked in a puff pastry crust with the addition of fresh thyme, it’s to die for!
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Why You’ll Love This Recipe
- Something about this caramelized onion tart screams “fancy” without costing you an arm and a leg! It’s the perfect appetizer for a dinner party or a meal with your partner.
- Did I mention already that this recipe only requires SIX INGREDIENTS? What’s even better, these ingredients are widely available, cheap, and easy to prep.
- Onion is often treated as an ingredient that contributes to the overall dish. In this caramelized onion tart, it is finally the star of the show. Perfectly sweet, aromatic, and melting in your mouth!
- Cooking the tart upside down guarantees that the crust stays flaky and crisp. It’s a great technique to have in your culinary arsenal.
- Don’t be frightened by the amount of time it takes to cook this appetizer. Most of the cooking process is hands-off. You get to sit back and relax!
Six Key Ingredients
For me, the selling point of this recipe is its simplicity. Who could have thought that six simple ingredients can turn into something so delicious?
- Puff pastry provides a flaky and buttery base for the caramelized onions. Unlike many other pie and tart recipes, this one is baked upside-down to maintain the amazing texture.
- Onions develop a rich, sweet flavor with a deep umami undertone when cooked for a while. The caramelization process also achieves a soft and velvety texture that adds depth and complexity to this tart.
- The onion flavor is further enhanced with the sweet tanginess of balsamic vinegar and maple syrup.
- Salt helps to balance the flavors out, as well as highlighting the natural qualities of other ingredients.
- Fresh thyme is a great way to add aroma and a splash of color to the dish when you serve it.
Origins of Caramelized Onion Tart
The upside-down caramelized onion tart, also known as tarte Tatin aux oignons (in French), is a variation of the classic French dessert, which traditionally features caramelized apples baked beneath a layer of pastry that is then inverted to reveal the fruit on top.
The onion tart follows a similar method, producing a delicious savory appetizer. The upside-down caramelized onion tart is a variation that has become popular in contemporary cuisine, particularly in French-inspired or modern European cooking.
Is Puff Pastry Vegan?
While traditionalists may argue that butter contributes a distinct flavor and richness to puff pastry, commercial manufacturers prioritize other factors when choosing ingredients for mass production.
As a result, the puff pastry you find at the store is often free of animal products. Commercial manufacturers often opt for vegetable-based fats for several reasons:
- Cost. Vegetable fats, such as margarine or vegetable shortening, are typically less expensive than butter. Using these alternatives helps keep production costs lower, making the final product more affordable for consumers.
- Shelf Stability. Vegetable fats have a longer shelf life compared to butter. This longer shelf stability allows for easier storage and distribution of commercial puff pastry products.
- Dietary Restrictions. By using vegetable fats instead of butter, commercially produced puff pastry becomes suitable for individuals who follow a vegan diet or are lactose intolerant. This broadens the potential consumer base for the product.
- Consistency. Vegetable fats can provide a more consistent texture and flavor to puff pastry compared to butter, which can vary in quality and flavor depending on factors such as origin and processing.
Remember to check the list of ingredients when you purchase puff pastry for this recipe! I like to shop in the freezer section of the supermarket. This way, I always have some puff pastry in stock to make this onion tart!
How to Make This Recipe
If using frozen puff pastry, check the package instructions on how to thaw it. Meanwhile, peel the onions and cut them into thick slices (about 1/2 inch thick).
Heat a large pan over medium heat. Arrange the onions evenly along the bootm of the pan and add enough boiling water to submerge the onions.
Allow them to simmer on medium-low for approximately 20 minutes until all the water has evaporated.
Add balsamic vinegar, maple syrup, and a sprinkle of salt. You can also add a drizzle of olive oil. Wait for the onions to caramelize slightly and change in color.
Preheat the oven to 400F and grease a pie or tart pan, approximately 8.5 by 10 inches, with oil.
Transfer the caramelized onions to the pan, trying to layer them as evenly as possible. Stretch the puff pastry sheet over the top and tuck the pastry in around the onions.
Bake your tart in the oven for 30 minutes, until the pastry is crispy and puff. Take the dish out of teh oven and wait for it to cool down until it is safe enough to handle.
Use your oven mitts to flip the pastry onto a serving platter or cutting board. Top with fresh thyme and enjoy immediately.
Hack It!
- Puff pastry is not the only option for this tart’s crust. If you’re gluten-free, you can use the same technique with a different homemade or store-bought pastry.
- This tart works with other types of vegetables, too! Try it with maple glazed carrots, Brussels sprouts, or roasted potatoes.
- If you’ve run out of maple syrup, use the sweetener of choice. Brown sugar, coconut sugar, or date syrup are my top-3 substitutes.
- Similarly, instead of balsamic vinegar, you might enjoy this recipe with apple cider vinegar.
Other Recipes You’ll Love
- Vegan Mushroom Wellington
- Scarpaccia Zucchini Tart
- Crispy Vegan Taquitos
- Bang Bang Broccoli
- High Protein Flatbread
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The Recipe: Caramelized Onion Tart
Ingredients
- 200 gram puff pastry, one sheet, thawed
- 4 red onions, or small yellow onions, sliced thick
- 1 tbsp balsamic vinegar
- 1 tbsp maple syrup
- 1 tsp salt
- Fresh thyme, optional
Equipment
Instructions
- Thaw puff pastry according to package instructions.
- Peel the onions into thick slices, approximately half an inch.
- In a pan over medium heat, disperse the onions evenly. Pour over boiling water until covered, and then leave to simmer for 20 minutes, until the water has evaporated.
- Add the balsamic vinegar, maple syrup, a drizzle of olive oil and a sprinkle of salt. Allow the onions to caramelize slightly, until browned. Remove the pan from the heat.
- Preheat the oven to 400F. Prepare a pie or tart pan, approximately 8.5 x 10, with oil.
- Disperse the cooked onions in an even layer in the pan, then layer the puff pastry over top. Tuck the pastry around the onions.
- Place in the oven for 30 minutes, until the pastry is browned. Carefully, once cooled slightly, use your oven mitts to flip the pastry upside down onto a serving platter or cutting board. Garnish with fresh thyme, if desired. Slice and enjoy immediately, or store in the fridge for up to 3 days.