I love this salad because it transforms humble ingredients into something restaurant-worthy. The caramelized onions add depth and richness, while the spicy brown mustard dressing brings brightness and a subtle kick. It’s easy to prepare, versatile enough to serve with almost any main dish, and impressive enough for guests. The fact that I can make the onions ahead of time makes it even more convenient for quick weeknight meals or elegant dinners.
Ingredients
(Note: All ingredient amounts are listed in the recipe card below.)
3 red onions, sliced into thin half-moons 1/4 cup balsamic vinegar 1/2 cup olive oil 1 1/2 teaspoons kosher salt 1 teaspoon freshly ground pepper 2 large shallots, minced 3 tablespoons spicy brown mustard 1/4 cup red wine vinegar 2 heads red leaf, butterleaf, bibb, or looseleaf lettuce
Directions
I start by tossing the sliced onions with balsamic vinegar, 1/4 cup of olive oil, 1 teaspoon of salt, and 1/2 teaspoon of pepper.
I heat a large sauté pan over medium heat and add the onions. I cook them slowly, stirring every few minutes, letting the mixture reduce and caramelize. If the onions start to crisp or the glaze becomes too thick, I lower the heat. I continue cooking for about 30 minutes, until they’re soft, glossy, and golden brown. Once done, I set them aside to cool slightly.
While the onions cool, I prepare the dressing. In a small bowl, I whisk together the minced shallots, spicy brown mustard, red wine vinegar, 1/2 teaspoon salt, and 1/2 teaspoon pepper.
As I whisk, I slowly drizzle in the remaining 1/4 cup of olive oil, whisking continuously until the dressing is smooth and emulsified.
To assemble the salad, I place the lettuce leaves in a large serving bowl. I drizzle the vinaigrette over the greens and gently toss them to coat.
Finally, I top the salad with the caramelized balsamic onions and spoon over any remaining glaze from the pan for extra flavor.
Servings and Timing
This recipe serves 4 people. It takes about 5 minutes to prep and 25–30 minutes to cook, for a total time of around 30 minutes.
Variations
I like to add crumbled goat cheese or feta for creaminess or sprinkle toasted nuts like walnuts or pecans on top for crunch. If I want a heartier version, I toss in some roasted beets or grilled chicken. For a fruitier twist, I sometimes add thinly sliced pears or dried cranberries—they balance the savory onions beautifully.
Storage/Reheating
I caramelize the onions ahead of time and store them in an airtight container in the refrigerator for up to 3 days or freeze them for up to 3 months. Before serving, I bring them to room temperature or warm them slightly in a pan. Once assembled, the salad is best enjoyed fresh, as the greens can wilt if dressed too early.
FAQs
Can I roast the onions instead of caramelizing them on the stove?
Yes, I sometimes roast them at 400°F for 20–25 minutes, stirring occasionally, until tender and caramelized.
Can I use yellow or white onions instead of red?
Absolutely. Red onions add color and sweetness, but any variety works well.
Can I make the dressing ahead of time?
Yes, the vinaigrette keeps well in the fridge for up to a week. I just whisk or shake it before using.
How can I make this salad vegan?
It’s already vegan-friendly! Just make sure to use a plant-based mustard and vinegar.
Can I add protein to make it a main dish?
Yes, I love adding grilled chicken, shrimp, or even steak slices for a heartier meal.
What lettuce works best for this salad?
I prefer tender greens like bibb or butterleaf, but mixed greens or arugula also pair beautifully.
Can I use Dijon mustard instead of spicy brown mustard?
Yes, Dijon adds a smooth tanginess if I want a milder flavor.
How do I keep my onions from burning while caramelizing?
I keep the heat on medium or low and stir regularly to prevent sticking or scorching.
Can I serve this salad warm?
Yes, I often serve it slightly warm—the contrast between the warm onions and cool greens is delicious.
What can I serve this salad with?
It pairs wonderfully with roasted meats, grilled fish, or a crusty loaf of bread for a light meal.
Conclusion
This Caramelized Onion Salad is one of those recipes that proves simple ingredients can make an unforgettable dish. I love the combination of sweet, tender onions, crisp greens, and tangy mustard vinaigrette—it’s fresh yet comforting at the same time. Whether I’m making it as a side for dinner or a standalone lunch, it always feels elegant, flavorful, and satisfying.
A vibrant, flavorful Caramelized Onion Salad featuring sweet balsamic onions, crisp greens, and a tangy mustard vinaigrette. Perfect as a side dish or light main, it’s simple yet elegant and full of depth.
Total Time:30 minutes
Yield:4 servings
Ingredients
3 red onions, sliced into thin half-moons
1/4 cup balsamic vinegar
1/2 cup olive oil, divided
1 1/2 teaspoons kosher salt, divided
1 teaspoon freshly ground black pepper, divided
2 large shallots, minced
3 tablespoons spicy brown mustard
1/4 cup red wine vinegar
2 heads red leaf, butterleaf, bibb, or looseleaf lettuce
Instructions
Toss sliced onions with balsamic vinegar, 1/4 cup olive oil, 1 teaspoon salt, and 1/2 teaspoon pepper.
Heat a large sauté pan over medium heat. Add the onions and cook slowly, stirring occasionally, for about 30 minutes until soft, glossy, and caramelized. If they start to crisp, reduce the heat. Set aside to cool slightly.
In a small bowl, whisk together minced shallots, spicy brown mustard, red wine vinegar, 1/2 teaspoon salt, and 1/2 teaspoon pepper.
Slowly drizzle in the remaining 1/4 cup olive oil while whisking to emulsify the dressing.
Place lettuce leaves in a large bowl. Drizzle with vinaigrette and toss gently to coat.
Top with caramelized onions and spoon over any remaining balsamic glaze from the pan. Serve immediately.
Notes
Add crumbled goat cheese or feta for a creamy element.
Sprinkle toasted walnuts or pecans for crunch.
Include sliced pears or dried cranberries for a sweet contrast.
Roast onions instead of caramelizing for a hands-off version.
Serve slightly warm for a cozy flavor balance.
Store caramelized onions separately for up to 3 days; assemble salad just before serving.
