Steak Salad with French Onion Dressing

As the air turns crisp and leaves begin to fall, it’s finally soup and warm-salad season. French Onion Soup inspires comfort with deeply caramelized onions, savory beef notes, and a rich cap of melted gruyère. Those beloved flavors are the foundation for this French Onion Steak Salad — a hearty, savory dish that brings soup-like warmth to a composed salad. It combines marinated flank steak, jammy caramelized onions, peppery greens, and a creamy French-onion–style vinaigrette finished with a scatter of gruyère.

This salad captures everything that makes French Onion Soup special without being overly heavy. Caramelized onions deliver deep, sweet-savory notes; the marinated flank steak adds robust, meaty richness; and a thick, creamy vinaigrette made with caramelized onions ties the components together. A dusting of finely grated gruyère gives the dish its signature, comforting finish. It’s an elegant weeknight dinner, a great option for entertaining, and a satisfying way to celebrate fall flavors.

French Onion Steak Salad

Ingredients

For the Steak

• 4 Tbsp. extra virgin olive oil, divided
• 2 Tbsp. red wine vinegar
• 1 Tbsp. sherry vinegar (or substitute balsamic vinegar)
• 1 heaping Tbsp. Dijon mustard
• 1 tsp. dried thyme
• 1 ½ lb. flank steak, cut in half widthwise and patted dry
• 1 ½ tsp. kosher salt
• ½ tsp. cracked black pepper

For the Onions

• 1 Tbsp. olive oil
• 2 medium yellow onions, thinly sliced (about 3 cups)
• ½ tsp. kosher salt
• ½ tsp. freshly cracked pepper
• 1 tsp. fresh thyme leaves
• 2 Tbsp. red wine vinegar
• 1 Tbsp. water (to help deglaze if needed)

For the Dressing

• ⅓ cup extra-virgin olive oil
• 2 cloves garlic, minced
• ¼ cup caramelized onions (reserve from the onions preparation)
• 3 Tbsp. red wine vinegar
• 2 Tbsp. fresh lemon juice
• 1 tsp. honey
• 2 tsp. Dijon mustard
• 1 tsp. fresh thyme leaves
• Pinch of salt and cracked black pepper, to taste

For the Salad

• 4 cups thinly sliced lacinato kale
• 4 oz. baby arugula
• 1 cup thinly sliced rainbow radishes
• ½ cup finely grated gruyère cheese
• Flaky salt, for serving

Instructions

For the Steak

1. In a small bowl, whisk together 3 tablespoons of olive oil, the red wine vinegar, sherry vinegar, Dijon mustard, and dried thyme. Season the flank steaks generously with kosher salt and cracked black pepper, rubbing the seasoning into the meat.
2. Place the steaks in a gallon-sized zip-top bag, pour the marinade over them, and massage so they’re evenly coated. Remove excess air, seal the bag, and refrigerate for at least 30 minutes, preferably overnight. Before cooking, let the steaks come to room temperature for about 30 minutes.

For the Onions

1. Heat 1 tablespoon olive oil in a large sauté pan over medium-high heat. Add the thinly sliced onions, ½ teaspoon kosher salt, ½ teaspoon cracked pepper, and fresh thyme leaves. Cook uncovered, stirring occasionally, until the onions begin to soften and turn golden, about 10–12 minutes.
2. Lower the heat to medium-low, add 2 tablespoons red wine vinegar, and scrape up any browned bits from the pan. Continue to cook until the onions are deeply browned and jammy, about an additional 5 minutes. If the pan dries out, add water in tablespoon increments to prevent burning.
3. Reserve ¼ cup of the caramelized onions for the dressing and set the remainder aside to top the salad.

For the Dressing

1. In a wide-mouth jar or small blender container, combine the extra-virgin olive oil, minced garlic, ¼ cup reserved caramelized onions, red wine vinegar, lemon juice, honey, Dijon, fresh thyme, salt, and pepper.
2. Use an immersion blender or small blender to emulsify the dressing until it becomes thick and creamy, similar in texture to an aioli. The caramelized onions contribute body and a rich onion flavor.

To Cook the Steaks

1. Remove the steaks from the marinade and let any excess drip off. Heat a cast-iron skillet over medium-high heat and add the remaining tablespoon of olive oil. When the skillet is hot but not smoking, add the steaks without crowding — you may need to cook in batches.
2. Sear the steaks undisturbed to develop a good crust, about 3–4 minutes per side depending on thickness. For medium-rare, aim to reach an internal temperature of about 125°F (it will rise while resting). Transfer the steaks to a cutting board and rest for at least 5 minutes.
3. Slice the steak thinly on the bias against the grain and drizzle with any pan juices. Finish with a pinch of flaky salt.

To Assemble

1. In a large bowl, combine the sliced lacinato kale, baby arugula, half of the radishes, and half of the reserved caramelized onions. Add a spoonful of the thick dressing and use tongs to toss thoroughly. Because the dressing is dense, it will take about a minute of tossing to coat the greens evenly.
2. Transfer the dressed greens to a large serving platter. Arrange the sliced steak over the top, then scatter the remaining radishes, remaining caramelized onions, and the grated gruyère. Serve extra dressing on the side and finish with flaky salt to taste.

Notes & Tips

• The marinade improves flavor and tenderness; marinating overnight yields the best results, but 30 minutes will still add good flavor.
• Caramelizing onions slowly builds sweet, savory depth — monitor the heat and add small amounts of water if the pan becomes too dry.
• If you prefer convenience, you can use prepared caramelized onions, reserving a portion for the dressing as directed.
• This salad makes a comforting entree for a cozy dinner and is also easy to serve for guests. Leftovers keep well refrigerated for a couple of days; store steak and dressing separately when possible for best texture.

Nutrition information is a rough estimate and should be used as an approximation.

Photography by Eat Love Eats.